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PTS Slow Flight and Stalls
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Ground Instruction in Stalls and Spins; D. TASK: MANEUVERING DURING SLOW FLIGHT; ...B. Task: POWER OFF STALL: ...PTS Power-off Stall; ...Stalls...B. Task: POWER-ON STALLS; Power-on Stall; Power on Stall Break;. Imminent stalls; Stall Recognition; Stall Recovery; Nine Demonstration Stalls; ...Simulated Engine Failure Stall in Climb Followed by Gliding Turn; ...Stalls in Skids and Slips; ...Cross-controlled Stall; ...Elevator-trim Stall; ...Accelerated Maneuver Stall; ...Stalls During Go-Arounds; ...Accelerated Stalls; ...Secondary Stalls; Hammerhead Stall; ...The Heavy Yoke; ... Have a Stall on Me; Flight Maneuvers Set-up: ...Training Stalls vs Inadvertent Stalls; Slow Flight Skill Exercise and Emergency; ...Being Afraid of Stalls; ...Good Instruction Means Stretching the Limits; ...
Instruction about Stalls and Spins
A stall is a loss of lift and increase in drag that occurs when an aircraft is flown at an angle of attack greater than the angle for maximum lift. Failure to recover from a stall may result in a spin or secondary stall. All spins are preceded by at least a partial stall of one wing.
This is the speed at which the critical angle of the relative wind is exceeded. Stall speed is the basis on which other AFM or POH operational speeds are calculated.
Angle of Attack:
AOA is the angle at which the chord line of the wing meets the relative wind. Exceeding the critical AOA of an airfoil section will always result in a stall of that section. If the required AOA for flight exceeds the ability of the air to maintain a flow over the wing, the result is a separation of airflow, loss of lift, a large increase in drag and eventually a stall. The angle of attack where a wing produces the most lift is also the point where it stalls.
Stalls come from excessive AOA for the airspeed and not from the airspeed itself. A stall can occur at any airspeed, in any attitude, at any power setting.
Configuration affects the stall speed. The landing configuration will reduce the stall speed. The lower airspeed limit of the white arc is the power-off stall speed in landing configuration. The lower airspeed limit of the green arc is the power-off stall speed in the clean configuration.
Load factor is the ratio of the lifting ability of the wings to the weight of the aircraft and its contents. The stall speed increases proportional to the square root of the load factor. An inadvertent stall is more likely when preceded by an increased load factor. If the stall occurs at a speed exceeding the Va maneuvering speed the aircraft may warp, spindle or mutilate. All recoveries from stall and spins require a loss of altitude, increase in airspeed and the load factor in the pull up.
Center of Gravity:
The CG affects stability and stall or spin recovery. An aft CG reduces the control forces required to stall the aircraft these light forces can generate higher and destructive load forces. Extreme aft CGs lead to inadvertent stalls that can result in an unrecoverable flat spin. A forward CG will require a higher speed before a stall occurs. Higher elevator forces are required to raise the nose with a forward CG.
The stability of the aircraft is directly affected by weight distribution. As the weight of an airplane increases so does the stall speed. Higher weight results in higher stall speeds. This is because a higher AOA is also required. Maneuvering speed, Va, is lower at lower weight. The rule of thumb, for aircraft where speeds are not available for all weights, is to find the percentage of weight difference between the maximum and any reduced actual weight. Reduce your calibrated approach speed a percentage that is half the percentage of weight difference to figure Va(ref)..
Altitude and Temperature:
Altitude does not appreciably affect the indicated stall speed. Recommended indicated airspeeds should be used regardless of the elevation or density altitude.
Turbulence can cause stalls at much higher than normal speeds. A vertical gust or wind shear that changes the relative wind will increase the AOA. Pilots should fly in turbulence at a speed well above the indicated stall speed but below the maneuvering speed.
The pilot who is subjected to distractions is put in a situation of greatly increased risk of an inadvertent stall.
VIII. AREA OF OPERATION - SLOW FLIGHT AND STALLS
MANEUVERING DURING SLOW FLIGHT
REFERENCES: AC 61-21, OPERATING HANDBOOK, and FLIGHT MANUAL
P 1. Knows specifics of entering and flying in slow flight.
Aware of reasons for slow flight competence and hazards existing.
P 2. Selects entry altitude that will preclude descent no lower than 1500' or as assigned.
P 3. Stabilizes the airspeed at 1.2 Vs1, + 5 knots.
P 4. Makes coordinated straight and level flight and level turns, at bank angles and in configurations, as specified by the examiner.
P 5. Accomplishes coordinated climbs and descents, straight and turning, at bank angles and in configurations as specified by the examiner.
P 6. Divides attention between airplane control and orientation.
P 7. Maintains specified altitude +100', specified heading + 10 degrees, and specified airspeed +10/-5 knots.
P 8. Maintains the specified angle of bank, 30 degrees; maximum in level flight, +0/-10 degrees, maintains the specified angle of bank, not to exceed 20 degrees; in climbing or descending flight, +0/-10 degrees;, rolls out on the specified heading, + 10 degrees and levels off from climbs and descents within + 100 feet.
EX This constitutes flight where any inattention to bank, airspeed, or attitude will produce a stall. A minimum safe altitude might be 3000'. Climbs, descents, and level flight with turns may be directed with altitudes to be held within 100'. The examiner may ask for either or both explanation and performance. Not to be recovered from below 1500 feet. AGL, 1.2 Vso +5 knots airspeed, altitude + 100 feet, heading + 10 degrees. Maintains specified bank, not to exceed 30 degrees, +0 degrees and -10 degrees, climbing or descending flight not to exceed a 20-degree bank at + 0 degrees and -10 degrees. Rolls out on headings + 10 degrees, levels off in climbs, descent within 100 feet.
Initiate the configuration by using Carb Heat, reducing power, holding heading and altitude, and trimming for minimum control pressure. Any bank may require power to maintain altitude. Be smooth and careful. Full flaps may require full power.
It will be next to impossible to fly this configuration without full use of trim and knowledge of aircraft performance. The most important element is the smoothness of entry. You must be able to get to the desired speed while holding heading and altitude, hands off. Once attained the speed can be held throughout any turn or maneuver if the bank is 30 degrees or less and power is applied in anticipation of loss of lift. Slow flight is an exercise in the use of rudder. The aircraft requires much greater control deflection than in normal cruise flight but the smoothness of application must be maintained. Power and pitch changes must be in anticipation of actual requirements. We are flying with a narrower margin of safety above the stall
No flap minimum controllable: Full flap minimum controllable
Carb Heat ..............................Carb Heat
1500 RPM ............................1500 RPM
Hold Hdg/Alt .........................Hold Hdg/Alt
Trim Down 4 ..........................Full Flaps
2000 RPM/Rudder .................Full Pwr/Rudder
Power as required ...................Trim up 1
55 knots or slower ..................Power as required @ 40 knots or slower
If a steeper than 20-degree bank is called for then power should be used to compensate for loss of lift. Constant bank angle requires careful attention. You will be constantly making small changes in the yoke and rudder. More often than not you will be flying in a cross-control condition. You might find that the examiner will accept a greater speed" like 60 knots without flaps and 45 knots with full flaps. Remember any change in power will affect the trim and the airspeed unless trim is corrected. Discuss with the examiner what he feels to be desired before you get into the plane. You might even ask him to demonstrate. Can't hurt; might help. Listen, the sound will be your first indication of things going wrong.
Stall Avoidance Practice at Slow airspeeds
1. Assign altitude and heading to be maintained by student using trim until stall warning activated.
2. Demonstrate elevator and rudder trim effects along with left turning tendency and need for right rudder.
3. Demonstrate turns in this configuration without rudder.
4. Practice turns, climbs and descents.
5. Demonstrate flap use procedures in slow flight to avoid stall during application and removal.
6. Slow flight, with airspeed indicator covered, with change in flap configuration plus distractions.
--Retrieve from back seat
--Use E 6-B
--Locate ground targets
--Find emergency airports
--Perform 200 foot vertical Ss
Special considerations apply to twin-engine stalls. (Covered at length in AC 61-67C)
See instructional material on slow flight.
POWER OFF STALL
REFERENCES: AC 61-21, AC 61-67, operating handbook, flight manual
P 1. Knows aerodynamics of power-off stall. Discusses aerodynamics
of a stall which occurs as a result of uncoordinated flight.
(Spin entry) Emphasis shall be placed upon recognition of and
recovery from a power-off stall. Recognizes and recovers from
P 2. Selects an entry altitude that allows all maneuvers to be above 1500' AGL, or as recommended by examiner.
P 3. Establishes a stabilized approach in the approach or landing configuration, as specified by examiner.
P 4. Transitions smoothly from the approach or landing attitude to the pitch attitude that will induce a stall.
P 5. Maintains a specified heading, + 10-degrees, if in straight flight; maintains a specified angle of bank not to exceed 30-degrees, +0/-10-degrees; in turning flight, while inducing the stall.
P 6. recognized and announces the first aerodynamic indications of the oncoming stall, i.e., buffeting or decay of control effectiveness.
P 7. Recovers promptly after a stall occurs by simultaneously decreasing the pitch attitude, applying power, and leveling the wings to return to a straight-and-level flight attitude with a minimum loss of altitude appropriate for the airplane.
P 8. Retracts the flaps to the recommended setting, retracts the landing gear, if retractable, after a positive rate of climb is established; accelerates to Vy before the final flap removal, returns to the altitude, heading, and airspeed specified by the examiner.
EX Able to explain what causes an aircraft to stall, drop a wing, spin, and recover. Able to discuss flight circumstances where an accidental or intentional power off stall might occur. Able to demonstrate power off stall entry and recovery. Able to demonstrate from level or bank in full or partial stall. With or without flaps. All flight to be no lower than 1500 AGL.
Back side of power curve, initiated from stabilized approach landing configuration, induce stall while maintaining heading within 10 degrees, or in a bank + 0 and -10 degrees with no more than 30 degree bank. Recognizes and announces first buffet or decay of control authority, recovers promptly after stall occurs with minimum loss of altitude. Accelerates to Vy before final flap retraction, returns to altitude, heading and airspeed specified by examiner.
Establishes landing configuration specified, transitions to stall, recovers by pitch, power, rudder, minimum loss of altitude. retracts flaps and climbs at Vy as directed. No secondary stall, excessive altitude loss, spin, or flight below 1500 AGL shall occur.
In all past PTSs this stall as described in the present one, went by the name of Approach-to-Landing stall. A difference was that the power was maintained at 1500 rpm. Now the FAA PTS has created a monster. While the standard landing procedure is to be performed with partial power, the PTS landing stall is to be made as 'the' power-off maneuver required of all PP applicants.
The purpose of this stall is to emphasize that the addition of power will not break a stall, only reduction of the angle of attack will do that. Power is used to conserve altitude. The aircraft is configured for landing approach with full flaps and partial power. Power is taken off and a descent is entered only to be followed by a turn during which altitude is to maintained until the stall. At the stall break the pilot is expected to reduce the angle of attack, level the wings, add full power, and remove part of the flaps. While maintaining altitude the aircraft is cleaned up with further removal of flaps and a climb is initiated when speed permits.
Approach to landing configuration
--Also called the approach to landing stall
-- Full landing configuration a power off stall and recovery to clean-up and climb while not being distracted and then being exposed to major distraction. Note loss of altitude.
-- Student to raise nose into buffet, announce stall and recovers after the stall occurs with minimum altitude loss.
--Base to final cross-control stall
--Pitch increase to offset rapidly increase in sink rate
--Improper airspeed control
-- Commercial applicant is expected to recover as the stall occurs
When we do stalls we are seeking recognition and prompt, proper recovery. You, the student, are being taught awareness. How you become aware depends on many factors. Most important are the variations of the center of gravity that will affect how a stall is entered and recovery accomplished.
As part of the preliminaries the examiner will ask you to perform a weight and balance for the aircraft. Based on the results you may be expected to discuss how the aircraft will stall and recover based on this information. You should be able to answer basic questions as to how the weight and C. G. affects the aircraft's stall characteristics. Answer the question asked. Don't dig yourself into a hole by trying to explain more than you know. The examiner is looking for recognition. He wants to know if you can recognize and distinguish between an incipient, a full stall, and perhaps an aggravated stall. He will observe your entry into the stall as to speed, heading, bank, and control usage. Use of the rudder is of particular interest. Keep the ball centered in all turns. You may be questioned as to your knowledge of stall recovery. The proper sequence is of particular importance. Do you try to raise a wing by using aileron? Did you use rudder to keep a wing from dropping during the incipient phase? Did you initiate your climb without exceeding Vy? How do you handle distraction? Your instructor will try to expose you to all of these learning opportunities.
Don't hurry. Talk your way into, through, and out of the stall. At no point in this section does the text discuss CLEARING TURNS. Yet, failure to clear the area automatically fails the applicant. A very common fault of clearing turns is failure to make at least a 90 degree left and right turn while maintaining the same altitude. A left 360 is always a good alternative. In a C-150 any stall can be achieved with only two fingers behind the yoke. A full grip on the yoke tends to tighten. This gives the impression of pull and movement but is deceptive. It leads to inadvertent steep banks and down pressure on the yoke shaft. Use two fingers and pull up for the last 4 inches of movement. Do not use trim during stalls unless the examiner makes a specific request. Know how to make a smooth entry. The smoother the entry the more control you will have over the stall. Without flaps, apply Carb Heat, power off, while holding heading and altitude. When 60 knots is reached slowly and smoothly apply back pressure, yoke, and rudder. If a bank is required, do not let the bank exceed 20 degrees. Use the minimum bank allowed if you can hold it correctly. A common fault in all stalls that require bank is to let the bank angle increase. Remember to take out bank pressure on yoke gradually as the pitch and angle of attack increases. Holding the same yoke angle as entry will cause bank angle to increase as yoke is pulled back. While in the bank an incorrect application of rudder may cause one wing to drop abruptly.
This is a stall and may occur without the horn going off. The instinctive application of up-aileron will only make the situation worse. At the stall, regardless of whether its one wing or the nose, relax yoke pressure to allow the nose to go to or slightly below the horizon. Level the wings and apply full power with appropriate rudder. Set a climb attitude at best rate of climb. (About 65 knots) Prior to beginning stalls ascertain how far the examiner wishes you to continue your recovery climb.
If directed to use flaps, put in the assigned amount soon after the white arc is reached. Hold heading and altitude until 50 knots or lower is reached. Apply yoke pressure and bank with more generous rudder very gently and slowly. The stall break will be more abrupt with flaps but the recovery proceeds the same. As soon as power is applied start bringing up the flaps to 20 degrees and then milking. The most common faults of the flap stalls are failure to bring up the flaps and entering a secondary stall. With full power applied the full flaps secondary stall will probably lead immediately to a spin.
A full power, full flap spin requires that power be taken totally off and flaps raised before normal recovery procedures are initiated. Since a one turn full spin in a C- 150 can lose 1000 feet it is best never to do stalls below 3000 feet.
See instructional material on stalls.
REFERENCES: AC 61-21, AC 61-67 operating handbook, flight manual
P 1. Knows aerodynamics of power-on stalls and effect of uncoordinated
use of controls. This shall include an understanding of the aerodynamics
of a stall which occurs as a result of uncoordinated flight.
(Spin entry) Emphasis shall be placed upon recognition of and
recovery from a power-on stall. Recognizes and recovers from
P 2. Select entry that will complete all maneuvers above 1500' AGL, or recommended altitude, which ever is higher.
P 3. Establishes takeoff or departure, configuration, airspeed and power specified by the examiner.
P 4. Transitions smoothly from the takeoff or departure attitude to pitch attitude what will induce a stall.
P 5. Maintains a specific heading +10-degrees, if in straight flight; maintains a specified angle of bank not to exceed 20-degrees, +0/-10-degrees, if in turning flight, while inducing the stall.
P 6. Recognizes and announces the first aerodynamic indications of the oncoming stall, i.e., buffeting or decay of control effectiveness.
P 7. Recovers promptly after a stall occurs by simultaneously decreasing the pitch attitude, applying power as appropriate and leveling the wings to return to a straight-and-level flight attitude with a minimum loss of altitude appropriate for the airplane.
P 8. Retracts the flaps to the recommended setting, retracts the landing gear, if retractable, after a positive rate of climb is established; accelerates to Vy before the final flap removal, returns to the altitude, heading, and airspeed specified by the examiner.
EX Explain the effect of power on the stall. Show how the failure to use adequate rudder to compensate for power affects the stall. Discuss the flight situations where such a stall might be expected. Explain recovery as being by pitch, power, rudder, for minimum loss of altitude. retract flaps and climb at Vy as directed. No secondary stall, excessive altitude loss, spin, or flight below 1500 AGL shall occur.
The student will establish the aircraft in a takeoff/departure configuration at approximately lift-off speed or as specified by examiner. A bank may or may not be required. The amount of power is usually specified as full except during entry. No lower than 1500 feet AGL, takeoff or departure configuration, induce the stall while maintaining heading within 10-degrees or in a turn no more than twenty degrees +0 or -10 degrees. Recognizes and announces buffet, first signs of control decay, recovers as stall occurs. To Vy before final flap retraction, returns to altitude, heading, and airspeed specified by the examiner.
This is the stall likely to occur during take off. In higher-powered aircraft a trim set for landing assist can precipitate this stall. This is a good reason to check trim prior to takeoff. A bank assumes an effort to avoid an obstruction. Limit bank to 20 degrees since a 30-degree bank is more likely to lead to misuse of the rudder and a wing drop as consequence. The slower your entry speeds the less pitch up when power is applied. Anticipate all power applications with rudder since applications are more likely to lag than lead.
Again, CLEARING TURNS. Talk through the entry, stall, and recovery. Talking explains to the examiner how you understand the process. Carb Heat, Power to 1500 or as specified, slow to lift off of 50 knots, hold heading and altitude, full power (rudder), and bank as directed. If you are not directed to bank, don't. Since the test will allow as little as a 10-degree bank, use that, but no less if so directed.
Slowly, smoothly but constantly, increase the back pressure. Apply rudder as the pitch attitude increases. The aircraft will gain altitude, may attempt to increase bank if a bank is required. The important element is to keep applying pressure until the stall occurs. Any abrupt back pressure will aggravate rudder errors and cause sharp wing drop. All too often pilots fail to get full back and up yoke and so continue to fly the plane at the edge of the stall. Don't forget the yoke is not all the way back until you pull it up. As pitch attitude increases so will required rudder pressure. All stalls are performed at altitude.
Since the power dramatically increases the pitch attitude, the stall break will be abrupt. Allow the nose to drop to or slightly below the horizon, level the wings, confirm full power, and initiate climb at best rate.
--Also called the departure stall or go-around stall
-- Straight and turning stalls initiated at lift off speeds with variable power settings
--Takeoff, go-around and climb out situations
--Trim and improper flap retraction
--Airspeed control on takeoff
--Repeat exercise but introduce major distraction at point of stall.
--Student to announce buffeting or control decay and initiate recovery by reducing pitch and using power.
--Commercial requires holding heading or up to 20 degree bank. Announces stall and recovers
Students who have had a turning problem during their training in stalls should be told that the problem is directly related to the gradual entry they make into the stall. The entry into the stall should not be initiated until the aircraft has slowed to near the Vmc. The more slowly you are going in level flight the more rapidly you can initiate the stall without excessive gain in altitude and abrupt break.
Recently, I had a student whose initial entry resulted in a gain of over 500' before the stall break. He initiated the stall at over 80 knots. After slowing to 60 and then 50 knots before initiating the stall the gain was 100' with 2000 rpm and 100' with full power.
The effects of p-factor and the other turning tendencies are dynamic and the longer the entry takes the more likely the turning tendency is to enter the picture. As airspeed deteriorates, the turning tendencies increase. You add more right rudder as you approach the stall. You can no longer see over the nose so you have a choice between using peripheral vision over the nose or watch the heading indicator. You use rudder to hold the heading while keeping the ailerons level. Any use of the ailerons will introduce adverse yaw and roll spin input. Done properly the stall break will be straight ahead even when performed in a turn.
As the stall occurs, smoothly lower to nose to or slightly above the horizon. By not reacting abruptly the entire maneuver and recovery can be accomplished in 100'.
Tractor aircraft require right rudder as the nose is raised into a power-on stall. Failure to maintain coordination will require even more rudder. Failure to maintain coordination will precipitate a wing drop and incipient spin entry.
1) Every stall must keep coordinated rudder to prevent the effects of yaw.
2) If the nose does not turn (Outside or HI reference.) the wings will remain level and the stall break will be straight ahead.
The major difference between this stall segment and those proceeding is the "depth" of the stall. In this procedure regardless of the configuration the recovery is initiated at onset. In the preceding segments no recovery was to be initiated until the actual "break" had occurred. The initiation as before begins with CLEARING TURNS. After obtaining the assigned airspeed, flap setting, power, and bank, commence the entry.
The more slowly you enter the stall, while holding heading/altitude as required, the quieter and more easily heard and felt will be the signs of the stall. If anything, the imminent stall should be approached more gently than a full stall. One should always be light on the controls. You should accept that being light does not mean that you should not be positive in your application. As you approach the stall one wing, the retreating wing, will tend to stall first. This stall, and the retreat can be corrected and prevented through use of the rudder.
With aileron application against the lowered wing, you are increasing the angle of attack of this low wing and taking it even more into the stall. Since the wing continues to drop, the instinctive reaction of even more up aileron only aggravates the stall. Any yaw derived from the rudder will initiate a spin.
The recovery of the imminent stall can be a very smooth gentle process with final recovery in a climb configuration. Again discuss with the examiner how far he wishes you to hold the climb. All disqualifying elements of the full stall apply to an imminent stall. Since the emphasis here is on recognition, letting a full stall develop would probably be disqualifying.
There are several stall indicators. The PTS expectation is that when any one of the stall indicators is noted the recovery should be initiated unless the intent is to achieve a full stall. Stall maneuvers should all be conducted at altitudes that allow recovery above 1500 feet for single engine aircraft.
--The stall indication are because of the angle of attack not the airspeed or attitude.
---Mushy controls along with decreasing control effectiveness
---The rpm decreases
---Exterior air flow noise decreases with change in pitch
--Stall warner begins to whimper
--Physical kinesthetic warnings of the body occur
--Buffet, vibration, pitching, sounds
See instructional material on stalls
Most pilots flying today do not use their feet correctly because of their training. The sad part is their instructors were not trained properly to know how to recognize poor rudder control, or how to correct the mistakes. Have had the student handle the aileron control while instructor does the rudder for stall entry and recovery, then reverse the roles.
A coordinated stall is a stall where the nose of the aircraft will drop straight away, without any wing drop. For a given aircraft and configuration different rudder inputs may be required. The student needs to be able to identify the beginning of a spin, i.e. the wing drop. If the student has been taught to identify this wing drop, he can correct for it with rudder before a spin has a chance to develop.
Recognition of the onset of a low speed yaw will also be useful in those low altitude situations where only immediate and correct action will save your life. One way of doing the correct thing is to use the opposite rudder to bring up the dropped wing.
---Initially the pilot must reduce the angle of attack.
---The amount of forward pressure is a variable but should not impose a negative load on the wing.
---Next comes power application to increase speed and minimize loss of altitude.
---No recovery should exceed redlines of power or speed.
Demonstration stalls are not required to proficiency. Instructors are expected to teach pilots the hazards of these stalls as a preventative. Students are not to practice demonstration stalls.
Engine Failure Stall in Climb Followed by Gliding Turn
Intention is to show hazard of turn back to airport following takeoff engine failure. Track altitude loss while using different angles of bank.
1. At altitude set up Vy climb referenced with parallel (simulated) runway.
2. Reduce power to idle at cardinal altitude.
3. Set attitude for best glide and make 260-degree gliding turn into any wind.
4. Make intercepting turn toward 'runway'.
5. Note altitude loss, airspeed loss and improbability of making runway.
in Skids and Slips
A skid has excess rudder...more than is needed in the turn. This, at a slow enough speed, will cause the low wing of the turn to stall before the high wing does. The excess rudder causes the aircraft to skid much as a car would on a gravel road turn. The wing that is low will continue to drop even more when the pilot tries to raise it with the aileron. A spin is imminent if top rudder is not immediately applied to raise the wing.
Unlike the skid, the slip has rudder applied against the bank. This causes the high wing, if it should stall, to stall before the low wing. This stall drops the wing and removes the slipping maneuver. The plane will come out of the slip and with neutral rudder will resume wing-level level flight. Skids are bad, slips are good.
Stall (Performed at altitude)
This occurs when ailerons are in one direction and rudder in the other. Simulate as making base to final turn with excess rudder. A skid.
Initiate a climb while keeping your feet on the floor of the
aircraft. Use the aileron to prevent any left turn. Gradually
increase the pitch attitude. At some point you will get the desired
cross-control stall. Be prepared to use rudder to get out of
the resulting incipient spin tendencies. It's a quick demonstration
and serves to emphasize the right rudder requirements required
in a climbing turn.
Student to perform from full landing configuration in a hands-off trimmed gliding descent. Then initiate go-around with full power while holding light right rudder and light elevator pressure until noses rises to critical angle of attack. Allow nose to pitch up and left yaw to occur. Recover at first indication of a stall by reducing pitch attitude. This is a go-around situation that requires considerable forward pressure to lower the nose while milking off the flaps for airspeed and then trimming off yoke pressure. Emphasize necessary attitude control, control pressures, flap removal and trim required during go-arounds. Objective is minimum loss of altitude.
The modified C-172 with power flow exhaust systems have sufficient power to surprise the pilot and reach this stall before being corrected. Do NOT trim for the flare as a safety measure. The go-around performed with trim applied for the flare can be deadly.
The accelerated stall can occur any time excessive backpressure is applied. The easiest way to demonstrate the occurrence and recovery is to enter a 45-degree bank at level cruise and gradually reduce power while holding altitude with backpressure. Any loss of altitude will defeat the stall intended. When stall occurs just level the wings. This stall is best recoverable with the ailerons.
1. Student to perform from full landing configuration a power off stall. Student to attempt to climb with flaps extended. Expect to stall.
2. Student to perform from full landing configuration a power off stall. Recovery is to be made with rapid removal of the flaps while holding a climb attitude. Resulting secondary stall and altitude loss should be noted.
---An accelerated stall occurs at higher than usual speeds.
---The stall may occur in high-speed pull up or in steep turns in level flight.
--- Accelerated stalls are usually unexpected.
A secondary stall occurs when the pilot tries to hurry the initial stall recovery without sufficient airspeed. Recovery is to first reduce AOA and do not initiate recovery until flying speed has been regained.
The correct way to recover from a tailplane stall caused by icing is to reduce airspeed. Trying to dive to increase speed only makes the stall deeper while pulling back makes the wing stall.
Actually Mike, a hammerhead should contain absolutely no backwards flight. In a hammerhead, you time the entry just before reaching the apex of the vertical line; hold neutral elevator; kick full rudder into and full aileron against the desired direction of rotation and allow the airplane to rotate on it's yaw axis. If done correctly, the airplane should go down the same line it used going up! Recovery is opposite rudder and neutral aileron to pin the vertical down line, power reduction, and easy back elevator to initiate recovery.
A whip stall can occur if the vertical line is held through total energy loss. Basically what happens is the airplane slides back on it's tail and swaps ends extremely fast. You are absolutely correct about the tail stress. In an aerobatic airplane designed for this loading, (even some aerobatic aircraft aren't designed to take this!!! ) you can initiate a recovery in either direction, forward, or backward, by the direction of elevator application during the slide backwards. In a non-aerobatic aircraft, (you shouldn't be vertical with no energy in such an airplane anyway)
It would be imperative that neutral elevator be held tightly as the airplane swapped ends on it's own. This would relieve some of the elevator hinge stress, but would result in a whipstall. Recovery would be power off, gentle controls to exit.
I should note here also that technically, it's impossible to experience an un-accelerated stall in vertical flight. (Notice I said, "un-accelerated".) You can still apply g and obtain accelerated stall in vertical flight. If left un-accelerated at the angle of attack produced in normal vertical flight, the airplane simply stops flying as energy depletes to 0.
Bottom line on whip stall; can be done at extreme climb angles if elevator is dumped as stall occurs, but realistically is considered the swapping of ends after reaching 0 energy in vertical flight without correction.
Hope this helps a bit.
Some of the 'heavy' yoke of aircraft has to do with the yoke movement combined with the geometry of the arm as it pulls back. The effect is that the arm pulls down on the yoke with a twist. This tends to bind the shaft of the yoke in its guide. And a slight drop in the left wing. Why students land on the left side of the runway? Sit in a chair and you will find that your elbow seems to move out with a twist as you pull back. This effect is more pronounced if you use a full fist grip on the yoke. This is a natural move that requires conscious effort to prevent.
The solution is to use one or two fingers to lift the yoke up and back. This prevents the binding and makes yoke movement backwards significantly easier. The net effect of this is a smoother and fuller application of elevator authority. In the past I have found the above both the cause and solution for an inadequate flare for landing.
a Stall on Me
A pilot is less vulnerable to an inadvertent stall who has a clear understanding of the aerodynamics of a stall and a ability to interpret indications of an approaching stall. Stalls occur when you try to get more performance than the plane is prepared to give. The stall most likely to be unexpected is when the down wing stalls first and tucks under even more. Only a slight touch of yaw will then give a spin entry. Recovery depends on skill and altitude.
Stall awareness is best retained through practice and frequent experience in a specific aircraft. Recognizing an impending stall and applying the appropriate corrective action will always prevent an impending stall. Inadvertent stalls are most apt to occur during turning flight. Increasing power when initiating a steep turn serves as a stall preventative. Stall recovery requires both skill and altitude. A violent stall requires a violent deduction of angle of attack. A gentle stall requires a slight reduction of attack angle for recovery. Most high performance aircraft can power their way out of a stall but if they can't the aggravated stall will be abrupt and violent.
Maneuvers Set-up (RSPP)
Used for emergencies, takeoff, stalls, steep turns, takeoff, taxiing, MORE
vs Inadvertent Stalls
--In the training stall the nose always drops thus causing a misconception.
--It is possible for the wing to stall without the tail stalling first. Thus no nose drop.
--A low airspeed high power situation can have the wing stalling with the elevators still effective.
--The aircraft is stalling, falling and the nose has not fallen.
--The downwash of a high-wing aircraft is more effective than the downwash of a low-wing aircraft.
--Therefore, the stall mush is more to be expected in high-wing aircraft.
--The extension of flaps in a high-wing plane increases the downwash and causes the nose to pitch up.
--Studies show that the initial stall-shake of a high-wing aircraft occurs at the rudder first then the elevator.
--An aircraft can get behind the power curve and locked into this stall and be unable to lower the nose. (Behind the power curve)
--Close to the ground lowering the nose is not a viable option often on landing or takeoff.
--Raising the nose only makes the situation worse the only options are increase power and milk off flaps.
--The stall/mush situation can be made more deadly if the pilot trims excessively for the landing flare.
--172s that have over 160 hp engines are subject to the surprise pitch-up stall due to trim position.
--Go-around power causes the trim-stall where the nose pitches up to a behind the power curve attitude.
--The high power can over-power the pilot's ability to hold the nose down due to flap or trim position.
--Low-powered aircraft in high-density altitude situations may not be able to climb out of ground effect.
--My standard instructional procedure on takeoff is to have pilot lower the nose to accelerate before climbing.
--In high density altitude situation do not rely on sense of speed for anything. Use only indicated air speed.
-- Pitching up may be diametrically the wrong thing to do when you are seeking the best climb attitude.
--When in doubt weight becomes a prime consideration. Unload, make multiple trips or cancel.
Slow Flight Skill
Exercise and Emergency 8-5-04
I flew a power, airspeed, heading, flap trim change exercise with a student today. He takes his checkride next week and I did the following with him to teach how to keep all the ducks in a row. Not a PTS requirement but nice to know how to do thing. Gave him far more confidence in his flying ability.
We were at 3200 over some hills. I had to student go to a moderate slow flight (60 knots) from level cruise holding heading and altitude. It took two tries before he could do the transition smoothly on altitude and heading. Then I had him add 10-degrees of flaps while maintaining heading, altitude and airspeed. Took two tries again to get it smooth. Then we went to 20-degrees of flap while maintaining all the parameters of altitude, airspeed, and heading. Finally we went to 30-degrees and did the same thing again. All of these were maintained within 50-60 feet but usually within 20 feet.
Just when he thought he was finished I had him undo the entire rocess.10-degrees at a time. Having done this successfully I told him to return to the airport. As he descended through 2000 feet I pulled the C.H. and power to 1500 rpm and told him that was all the power he would have to reach the airport. He immediately went to best glide and we made the airport on a base entry needing to use full flaps on final to get down. Student was amazed that we could go so far on such little altitude and power. Then I told him about the favorable tail wind in which we could have done better by flying about five knots slower.
Student wondered why we were able to do this seemingly impossible arrival. I told him that I learned to do it by having students do it first.
Being Afraid of Stalls?
Perhaps more correctly you are afraid to do your own stalls, alone. The good news is that you are not required to practice stalls alone. You will need to practice doing them with your instructor. You will need to demonstrate the PTS required level of stalls to an examiner. Thats as bad as it gets.
Stalls can become fun when you get some aerobatic training that carries the stall into a spin and into a recovery. You are not required to do this but most of you fears are emotionally based on hearsay. Spins, when performed at altitude, are no more dangerous than a roller coaster.
Given sufficient motivation any airplane will stop flying. An airplane stops flying when it stalls. This is not at all related to the stalling of an automobile engine. Over the years a disproportionate number of potential pilots have been dissuaded from becoming pilots by macho stall demonstrations. The roller coaster fun of an abrupt full stall is not fun at all to the unfamiliar passenger.
I have never, in all my thousands of stalls deliberately scared a passenger or student. On the other hand, I have been both surprised and scared by students. Most often students scare themselves by responding to a mild and gentle stall as though it would require a full yoke forward, nose down recovery. I do let students scare themselves. A stall is a prelude. It is the beginning of a potentially hazardous sequence of events. Avoidance and recognition precedes recovery. Stall recovery, commenced in a timely and correct manner breaks the sequence leading to a spin.
There is no FAA prescribed point in the flight training program where a stall must be introduced and performed. Each instructor/student combination can vary doing stalls as they desire. However the end result must allow the student to demonstrate both knowledge and performance of likely entries, recognition, and recovery as may be required by the examiners testing of the PTS requirements.
Stalls may be introduced in a series of small increments. Each increment is preceded by a mention the flight before by suggesting that we might try a stall of a certain type. The stall lesson flight is preceded by a ground discussion of clearing turns, the 10 knot lead in warning of the warner (ignore), the significance of the elevator burble, the stall break and the recovery to or slightly below the horizon.
The use of rudder to hold a heading is always in anticipation of the nose moving to the left and not in reaction. The yoke movement is in anticipation of a loss of altitude, related to the full stall landing, we are tipping the aircraft nose up while maintaining a constant altitude. This yoke movement is demonstrated on the ground as both back and up with a minimum of fingers used. Two fingers should be sufficient for most trainers. In the air, natural tension in the student will make even the clearing turns ragged.
Since I do all my instruction using a tape recorder, I seldom initiate the flight instruction with a demonstration, instead, I talk the student through the process and allow it to proceed with some instructor control (rudder usually) input. For the power off stall, we make clearing turns. Stop on a heading or visual reference, pull carburetor heat, pull the power off and allow the speed to decrease while holding heading and altitude. As discussed we are attempting to rock the nose of the aircraft up while maintaining altitude. The first time onset of the stall warner often causes the student to jerk and release pressure. Fine. We recover and start the process again. This time we proceed only until the first burble. As planned we (the student) relaxes pressure to allow the nose to fall slightly below the horizon, speed to increase slightly and once again we stop the altitude loss. This time we get to an incipient stall or possibly beyond. This time recovery is made through the use of power and rudder.
Enough? Probably, but not necessarily. Let the student set the stall lesson limits. With the students approval, but at the instructors suggestion the next stall lesson will include a ground review of the prior lesson and an introductory walk talk through the 2000 rpm straight ahead power-on stall. This is the stall that might be accidentally entered from slow flight. As before the talk/walk through begins with clearing turns and slow flight at 2000 rpm without the trim. Prior to entering the stall but while in slow flight the use of the rudder should be demonstrated. Alternately both the left and right rudder should be applied while the student is looking at the opposite wing. The rudder will move the wing forward, effectively increasing its speed and raising it. Do not do the stall until the student sees that the way to raise a dropped wing in the stall is by using the rudder and not the aileron.
The reduced power-on stall will result in an increase in altitude but the increase in pitch should be done as gently as possible while an ever-increasing amount of right rudder is applied. The ideal stall break is straight ahead, if one wing or the other drops it is because of rudder use. Most often the left wing breaks because of insufficient right rudder. Attempts to raise the wing with aileron will only exacerbate the stall in that wing. The nose of the aircraft should be lowered to or slightly below the horizon in any event. This particular stall can be smoothly repeated over and over within a 100-foot altitude range just by leaving the power alone. This is a good exercise in a subsequent lesson.
The additional phases of stalls such as the full power stall, the approach to landing stall, stalls in turns, and conditions leading to stalls are progressions of these basics. All of them should be introduced and flown with as much frequency and emphasis as the student is willing to accept. The instructor should never expect to teach the student to enjoy to stalls except in so far as the entry, stall, and recovery are smoothly performed. Increasingly, the PTS is reducing the extent to which various stalls are to be performed prior to recovery. My personal opinions aside, the PTS seems to be emphasizing recognition as being the essential ingredient to be followed by immediate recovery.
Means Stretching the Limits
I had fun yesterday. My CFI, a Brit, had me do a low approach down a long runway. I've never done that before, but I enjoyed keeping a 172 a few feet off the ground at 45 to 55 knots, full flaps down a 7500 foot runway. I'm not exactly sure how many feet off the runway we were, but based on the shadow from the sun I saw with my peripheral vision, I think it was between one and two feet. He said a pro air show pilot does it at about six inches, but less wobbly I'm sure.
We also did a simulated engine out under the hood, and spiraled down to the rural airport using the GPS display at 1 mile to line up on the downwind for the correct runway. I like to pull throttle and drop full flaps abeam the touchdown point and do a rounded base and final from there for my normal touch and goes to keep the pattern tight and the simulated engine out set up was perfect for that.
We also did the usually PTS maneuvers with lots of slow flight, including simultaneous climbs, descents and turns in slow flight. He said the multiple simultaneous slow flight maneuvers was like having me rub my head and my belly at the same time. I suppose I should have been tap dancing too. I didn't know you could maneuver a C-172 so much with the stall horn blatting, although I did know you can change the pitch of the stall horn with the yoke, like a trombone.
He made me use VFR flight following the whole time too, which was really nice when Approach pointed out a Piper on a nearly converging course.
My arms, shoulders and neck are still sore 24 hours later, so I know I had a good workout. Thank you for a good CFI who pushed my limits and made me learn.
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Continued on Page 2.6 PTS Spin Awareness