…Slow flight; ...Aircraft Stall Factors; ...Desirable Stalls; ...Trim in the Stall; ...Wings in the Stall; ...Rudder in the Stall; ...First Stall Instruction (Instructor); ...Stall Lesson; ...PTS Stalls; ...Objectives of Stall Instruction; ...Clearing Turns; ...Where to Practice; ...Not so Real Stalls; ...Stall Exercises (Instructor); ...Stall Avoidance Practice at Slow Airspeeds; ...Stall Recognition; ...Natural Stall Warning; ...Generic Stall Recovery; ...Secondary Stall ; ...Stalls Down Low; ...Deep stall; ...Stall Recoveries; ...Stall Proficiency (Instructor); ...Power-Off Stall; ...Power-on Stall (Partial power); ...Departure Stall; ...Approach Stall; ...Accelerated Stall (Instructor); ...Accelerated Stall Situations; …Cross-control Turn Base to Final Stall; ....Unrecoverable stall; ...Trimmed Go-around Stall; ...Engine Failure at Altitude; ...Takeoff Engine Failure Stall; ...Engine Failure on Final Stall; ...Landing Flare Stall; ...Premature Flap Retraction Stall; ...Go-around in a Right Crosswind Stall; ...Slow Flight in Pattern Stall; ...Short Field Takeoff Stall; …Falling Leaf Stall; ...More on Stalls; ...Stall Review; ...Stalls in Brief; …Stall Strip; …Is a Stall Coordinated? ...
Most any one can skate or ride a bike fast. It is at slow speeds that true skill and control can be demonstrated. The same is true about flying. When I first sought to be a flight instructor an old time CFI took me out on his nickel and told me that we would explore the outer-limits of the aircraft's controllability. Under his guidance I learned to fly. Prior to that I only had control.
We would fly without flaps on heading and altitude with power as required to maintain level flight. We would fly slow, slower, and slowest. We flew well below the 10-knot margin given by the stall warner. A student is not expected to do this in any configuration. The PTS standards are to fly at Vs1 without flaps, with flaps, with partial flaps on heading and at altitude plus ten and minus five knots; within 100 feet of altitude and 10 degrees of heading. Then they add turns, climbs and descents with specified angles of bank.
Most any Vs1 slow flight can be performed in a ten degree bank. To the left just relax the rudder. To the right add rudder and opposite aileron. If you go beyond the 10-degrees you look forward to a cross-control stall. By adding some power you can make a 30 degree bank. Now the stall spin possibilities are increased. Time for a distraction to be introduced. Slow flight near the stall is called minimum controllable. The power of the rudder in controlling the stall and yaw is best demonstrated in this exercise. The proper rudder application is proven when the stall break is straight ahead without any wing drop. Any application of aileron will be counter productive by further stalling the wing and causing a more abrupt wing drop.
Aircraft Stall Factors
Wilbur Wright used the word 'stall' in 1904 to describe how in a turn Orville allowed the aircraft to pitch up too much and stall. The potential of an aircraft to stall or spin is in its design. A pilot's ability to detect and react to this potential is a criteria of flying skill. When an airplane is flown at an angle that exceeds the critical angle of attack, the airplane will stall. In deliberate training stalls we decrease airspeed and avoid the abusive control inputs that cause unusual attitude stalls. Low speed is not the cause of the stall; the cause is the angle of attack.
The pilot has control of the elevator. Pressures on the elevator determine if the wing will develop an angle of attack sufficient to stall. When the angular difference between where an airplane is pointed and the way it is going exceeds about 11 degrees to the wing's chord line a stall occurs. This is called the critical angle of attack. Exceeding the critical angle of attack of the wing with elevator inputs will cause the airflow to break from the upper wing surface. This break in air flow reduces the coefficient of lift, increases the coefficient of drag and transmits to the pilot a series of aerodynamic, mechanical and physiological cues.
Stall warners give a ten-knot warning of impending stalls as normally performed. The accidental inadvertent stalls that I have encountered occurred simultaneously with the sound of the horn. The same plane could stall at 40 knots when weighing 1600 pounds an at 30 knots weighing 1300 pounds. Of course, weight is always a factor in that a 20% weight increase will give 10% higher stall speeds. while a corresponding 20% reduction in weight will give a 10% lower stall speed. . The real objective is not so much performance as recognition by sight, sound, and feel.
The critical constant in stall speeds is weight. Book (POH) figures are based on gross weights. This provides most flight operations with a built in safety margin. This safety margin may be over-ridden by knowing that your actual weight is a certain percentage less than the gross. You can reduce your approach speed by a percentage that is half the percentage of lower weight difference. Some aircraft have critical approach airspeeds that do not follow the rule because of control and ability to go-around considerations.
I'm working my way through Gleim's FIRC (Flight Instructor Renewal Clinic) and came upon the statement that:...
"Load factor is the ratio of the total lift generated by the wings to the actual weight of the airplane and its contents [...] In un-accelerated flight, the load factor is 1; i.e., the total lift equals the gross weight of the airplane."
As a broad statement, that's true, but there's a nit.
The lift generated by the wings in level flight is the weight of the airplane PLUS the down-force generated by the tail. If you were being pedantic, would it not be more accurate to say that the load factor in level
flight is slightly greater than 1?
It just so happened that the immediately preceding question had to do with the decrease in stall speed as the CG moved aft, due precisely to the change in down-force of the tail, which is what got me thinking along these lines.
For those who may be a little weak in doing the figuring, make a proportion like this:
Difference between actual and gross = Percentage of gross
Gross weight 100
Cross multiply difference x 100 and divide product by gross weight to get percentage of gross.
200# = % 200 x 100 = 12.5% Taking half leaves 6%
1600# 100 1600
6% of a 60 knot approach speed is about three knots. 60 - 3 = 57-knots
This example can be used as a basis for interpolation only for the C-150.
When stalling speeds are determined for aircraft they are set at the most critical CG condition. Thus the speeds are set in the manual for "indicated" speeds with a forward CG position. This gives the highest stalling speed. Since training aircraft are seldom flown at the most forward CG the usual stall speed will be lower. This accounts for the book differences you should have noted. The way an aircraft behaves entering, during, and recovering from a stall is used to determine its stall characteristic. These characteristics are determined at the aft CG when stall speed is at its slowest.
A "stall" occurs as a result of one of two events:
1. The wings can not support the load of the weight being carried.
2. The horizontal tail can not provide the pitching authority needed to support the wing loading (tail stall)
3. 1 and 2 have to do with an aircraft that has exceeded its critical angle of attack.
The normal stall is when the wing stalls. When the tail stalls it is called a tail-stall. The tail stalls are very abrupt and the nose pitches down near the vertical. This stall increases the effective AOA of the tail. The stall can tuck the aircraft inverted with negative G-forces. The most desirable stall occurs when the wing root stalls first and moves outward to the wing tip. This desirable stall can be built into the wing by twisting the wing, adding slots to the wing tip, putting stall/spoiler strips to the leading edge of the root. The noise you first hear is the vibration of erratic air hitting the tail surfaces.
Every aircraft type and even aircraft of the same type will have stalling characteristics affected by weight distribution, wing loading, its critical angle of attack, control movement, configuration, and power. Higher powered aircraft can often be flown out of the stall by the addition of power. The purpose of such a stall recovery is to minimize any loss of altitude. This is a more aggressive stall recovery than the usual lower the nose technique.
Stall characteristics are often 'discovered' after the aircraft has gone into production. The manufacturer-government license agreement requires that all production aircraft adhere to original construction so some modifications are incorporated. The most expensive fix is construction of a leading edge slot. A 'cuff' or drooped leading edge may be used, a series of protrusions on the upper wing surface may be used to direct air flow even to the extent of being full chord 'fences' to prevent span-wise flow. The addition of a small triangular strip on the leading edge of the wing can cause the airflow over the surface to break and burble sooner than otherwise. This, rather common, method, is the least expensive fix of all. The design should be such that the stall occurs progressively from root to tip. The tips have a lower angle of attack than the root. Recovery of a stall begins at the tips and proceeds to the root. This design allow ailerons to remain effective for longer periods. This is a defense against the rudder-shy pilot who reacts with aileron for a wing drop rather than rudder..
Government stall tests are not made with slips or skids. While the old saw of slips being good and skids being bad may be true, it is only partially true. A stall that occurs in a slip or skid may occur at a higher speed than expected. Any deflection of the ailerons will increase the stall onset. Any aggravation of the stall by increasing the back pressure may result in sudden attitude changes due to turning and unequal wing speed. The attitudes resulting may be a combining of yaw, roll, and spin entry.
As the stall approaches the ailerons become ineffective first. Elevators
follow when the airflow from the wing becomes turbulent. This turbulence is
your natural stall warning. As the stall approaches, students tend to under
react with the required rudder pressure to keep the wing speeds balanced. A
more aggressive application of rudder in the beginning is more desirable.
When the stall occurs that will kill you it won't be at 2500 feet AGL….It won't be done intentionally and you won't expect it. It'll happen on short final, right after takeoff or on the go around from a short strip You'll be distracted (which is why you've allowed this to develop) and will need to make an immediate and proper corrective action. The only way to develop that reflex is with practice but not a low altitudes.
Trim in the Stall
Trim is not normally used to relieve pressure during the actual performance of training stalls. However the new PTS (Practical Test Standards) now calls for stalls to be made in a trimmed condition with distractions. A no power recovery should occasionally be called for. Any flaps more than 20 degrees should be taken off at once. Less than 20 degrees of flaps should come off when climb speed is attained. The apparent attitude of stalled aircraft with flaps is quite flat. Holding pitch attitude of the aircraft correctly while removing flaps is a must. No loss of altitude should occur while removing flaps. A secondary stall during recovery is indicative of failure.
Wings in the Stall
The manner in which the stall cues are transmitted is dependent upon wing shape, twist (washin/washout) and installed features such as strips, slots or flaps. Together these cues provide the pilot a warning of the stall onset. With washout the wing is mounted in a jig and twisted to lower the angle of incidence at the wing tip while being built.. Impact air on the bottom of the wing still provides some residual lift but not enough to keep the airplane flying.
Ailerons in the stall will only aggravate it. Ailerons change to chord line of
the wing to create lift and movement along the roll axis. When the aileron is
stalled, their movement causes roll that is contrary to what you either want or
expect. Once the recovery is initiated with forward yoke and rudder the use of
ailerons may or may not be helpful depending on the aircraft. This difference
is aileron effectiveness is related to the washin/washout or twist given to
the wing progressively toward the tips. Tips stall last and recover first in
most modern aircraft due to a decreased angle of incidence. Aircraft design
determines the aircraft stall characteristics.
A stall progression, if the same on both wings, will result in a straight ahead nose drop with no rotation about the roll axis. Not all stalls are symmetrical and the pilot will experience an abrupt drop of one wing or the other. The instinctive reaction to this by the inexperienced will be a reaction to lift the fallen wing by using the aileron. WRONG! Only the rudder can effectively stop the rolling of the aircraft. The falling wing can be decisively raised only with opposite rudder. This rudder causes the falling wing to increase in speed by moving forward. You may still be stalled but the rotation was caused by a non-symmetrical stall. Rudder can make the stall symmetrical without the rolling.
When the angle of attack reaches a certain point the drag is so great that full power will be inadequate to maintain altitude. At this point you are flying 'behind the power curve'. In this condition your only recourse is to sacrifice altitude by lowering the nose. Without sufficient altitude to allow the aircraft to resume un-stalled flight, this is not a viable option. This is the flight situation that arrives in entry to a full-power-on stall. With power full and stalled any misuse of the rudder or ailerons will precipitate a relatively quick spin entry.
Rudder in the stall
A spin can be prevented even when aggravated by the ailerons if the pilot maintains directional control through use of the rudder. A spin can only occur with the addition of yaw in the stall. The rudder can and should be used to prevent any yaw in the stall and the recovery procedure. The correct use of rudder in stalls is essential. The rudder controls the yaw which means it can keep the speed of each wing the same or cause one to be ahead (faster) than the other. The slower wing will stall first and drop. Any effort to raise the wing with aileron will add drag and deepen the wing's stall.
The rudder is the last control to lose effectiveness. Even in the stall if there is some forward momentum there is some degree of effectiveness. In a stall entry you first lose aileron control, then elevator and lastly rudder. On recovery, you gain rudder control first then elevator and lastly aileron. As the most effective control during slow speed maneuvers rudder, correctly applied, can compensate for the lost effectiveness of the ailerons. The rudder can be used to keep the wings level to the relative wind. Such level wings causes the stall break to be without a wing dropping. Keeping the ball of the inclinometer in the center gives assurance that the tail is following the nose. This is coordinated flight. If the heading indicator is held steady with a very gradual application of right rudder, little or no aileron movement will be required to keep wings level.
A student pilot's introduction to stalls will imprint his entire flying career. Practically everything written on stalls is inductive to terror. If the first stall is abrupt, violent, and with sharp wing drop every instinctive reaction will aggravate and prolong the student terror. Instead, the instructor should put the student in charge and begin a slow smooth gentle entry with rudder control closely monitored by the instructor. Very gradually over the entire training period the stalls may/should be aggravated. The student introduction to turbulence and weather should be just as gradual both as to duration and severity. The better a pilots knowledge of wind and weather patterns the better able he will be to select desirable conditions. There is nothing wrong with not enjoying either stalls or turbulence.
Stalls should be introduced on the second flight.... gently. After clearing turns expose the student to the nose drop that occurs on power reduction. Repeat the power reduction and have the student hold the nose level with the yoke. Have the student apply carburetor heat and reduce the power to off while holding the nosed to prevent loss of altitude. The yoke movement should initially be very gradual and increase logarithmically as speed decreases. The last few inches of yoke movement should be UP and back.
The recovery must be positive in reducing the angle of attack but not more than required to lower the nose to or slightly below the horizon. The abruptness of the recovery should be in direct proportion to the abruptness of the stall. Any recovery action in excess of what is needed to return the wing to an effective angle of attach can only delay the recovery and cause an excessive lost of altitude. At the same time, full power is applied to increase speed and thereby reduce the angle of attack. Some aircraft have sufficient power to literally fly out of a stall. The final recovery is to resume coordinated use of the flight controls.
Proficiency stalls are those stalls expected of the pilot applicants. Included in stall training will be such demonstration stalls as the accelerated stall and the oscillation stall which are not required except for flight instructor tests. Demonstration stalls are not part of the PTS but should be taught and demonstrated since they can occur when you least expect them.
Introduce this lesson in slow cruise where you allow the student to look to the wing tips and note that the rudder can be used to make one wing move forward of the other. Knowing this, advise the student that in a stall he should always step on the high wing. Oscillation stalls are performed in a power-off and clean configuration. The yoke is continuously held back from a gentle and smooth entry. The rudder is used to raise any wing that should drop and start a roll. Always step on the high wing. In a stall use full rudder with rapid movement to catch a falling wing before it gets down too far. Hold the yoke level to cockpit.
PTS wants 20-degree banks for power-on stalls and up to 30 degrees for power-off stalls. The stall recovery puts the nose on or very slightly below the horizon. The pilot applies full power and corrects for any stall-induced roll with the rudder.
The objective of stall practice is to develop awareness of the mechanical and physiological cues that precede the stall along with the appropriate reactions to effect recovery. We practice intentional stalls so that we can react appropriately to the consistency and predictability of a given aircraft. Instinctive control reactions are both wrong and potentially dangerous. Modern aircraft have opposite ailerons with differential travel to reduce but not prevent the dangerous aspects of improper or inappropriate aileron movements. Appropriate reaction requires coordinated use of the rudder and forward elevator to reduce the angle of attack. Even the best combinations of these features can be offset by weather (icing), weight, loading and power. The more violently a stall is entered the more violent will be its break. Recognizing the sight, sound and touch of a stall entry is to be followed by an immediate reduction of pitch attitude.
There are three purposes for instruction in stalls, none of which have to do with the actual stall performance:
--We want a pilot to be familiar with the flight conditions most likely to precipitate a stall. --The second objective in stall instruction is for the pilot to become familiar with the sight, sound and feel of an approaching stall.
--The third, and last purpose, is that the pilot take immediate and proper corrective action.
Knowing where stalls are likely to occur is the second awareness objective of practicing stalls. By practicing a variety of stalls at altitude you learn enough about your aircraft to know how much forward yoke movement is required for recovery along with how much altitude is required. The availability of power makes a significant difference in the recovery attitude and procedure. Remember that your right leg and foot use accompany applying power to prevent yaw. Some aircraft have sufficient power to effectively fly out of the stall; others do not. Know your airplane.
The reason for doing training stalls is to help the pilot overcome the dangerous instinctive reactions and to initiate an immediate stall recovery based on 'knowing' what to do. Proximity to the ground is an inhibiting factor that must be overcome. Regardless of altitude the elevator control must be moved forward to reduce the angle of attack, only then can the stall recovery be initiated.
There are certain aspects of training stalls that are the same for all of them. Every stall should (must) be preceded by 90 degree clearing turns left and right. (The clearing turns should be as precise as to amount of turn, angle of bank, altitude, and heading as though they were part of the stall process.) The well performed practice stall will result in an initial loss of 100'. The actual stall may be called as incipient, partial, full, or aggravated. The longer a stall is aggravated or held, the more airspeed decreases. This means either more power or altitude will be required during recovery. The recovery is always with full power, no flaps, in a climb, and at best rate of climb speed (65 kts). An old FAA recommendation was that 300' be gained during recovery but the time required is not practical in many cases. Trim for any climb.
Where to Practice
One major problem of instruction is where to go to safely practice stalls. Since you will be flying in all directions during this period you want to be within 3000' of the earth's surface. Avoid flight at altitudes where the hemispheric rule applies. You try to find an area clear of an active fly way between airports and preferably clear of any airways or vectoring routes. I have found it best to operate over mountain ridges and plateaus which allow legal operations at such altitudes as 4300' or 3800'. This gives some additional glide range to the lowlands. I would avoid any operations at even thousands of feet as well as those at the 500s' since you will be exposed to either IFR or VFR transient aircraft. I have often utilized radar advisories where available during these training operations.
On a particularly poor visibility and ceiling day, I obtained a Class Delta clearance to practice in the top 600' of their airspace. I was above arrival/departure traffic and any traffic 'should' obtain a clearance to get where I was. Just monitor the radio and have a good time right above the airport.
Not so Real Stalls
It is nearly impossible to create a 'practice' stall that has all the qualities of an unintentional stall. However, the recovery from both the intentional and unintentional stall will be the same. Efforts to create the accidental or unintentional stall may be so emotionally traumatic that the mere mention of a stall causes an anxiety attack. The mental and emotional attitude of the student toward a stall and the recovery is perhaps more important that the actual performance.
The deliberate stall is an integral part of a normal landing. The student should be talked through a landing to understand how the aerodynamics of a stall with all of its control feel and sinking sensations makes the landing possible.
Power is not needed either to perform or recover from a stall. (Use a paper airplane to demonstrate) The use of power in the stall will make for a higher angle of attack and power in the recovery will reduce the loss of altitude. The essential of any stall recovery is to be decisive, deliberate and timely in the recovery.
As such, the procedural "stall" we learn, practice, and mimic for the examiner bears little-to-no resemblance whatsoever to real-life inadvertent stall/spin scenarios--the stuff we as pilots must be on guard for and be prepared to deal with. In fact, one Princeton University study revealed the following about stall-only (no spins!) fatal accidents:
--60 percent of the cases, turning flight preceded the fatal stall accident.
--Turning and/or climbing flight preceded 85 percent of the fatal stall accidents.
--Only 15 percent of fatal stall accidents involved neither turning nor climbing prior.
Select an altitude that is less than 3000' AGL over a single hill that is not at an even thousand or five-hundred. In a C-150 make clearing turns. Apply carburetor heat and reduce power to 1500 and hold heading and altitude while airspeed decreases to 60 knots. Increase power to 2000 rpm. Trim for 60 knots. Have the student slowly but constantly raise the nose to the first whimper of the stall horn and then lower the nose to return to original altitude at 60 knots. Use the rudder to maintain heading. Do it again but get a more pronounced stall warner before recovering. Do it again and reach the first aerodynamic signs of a stall before lowering the nose and recovering. Continue into progressively more deeply into the stall up to a full stall and recovery. All of this maneuver can be performed within 100' of altitude with no change in power setting.
Show that any 'wing drop' is due to a rudder problem and that using the
aileron will not solve the problem but rudder will.
Stall exercises (Instructor)
The great weakness in stall/spin training is that it is unsafe to practice or simulate those situations that are most likely to surprise a pilot. We can teach and train for:
Stall Avoidance Practice at Slow
1. Hold heading and altitude while reducing power and trimming.
2. Hold heading and altitude with stall warner on.
3. Demonstrate elevator trim from neutral to full up.
4. Note left turning tendency and rudder effectiveness.
5. Demonstrate required right rudder.
6. Demonstrate rudder effect by releasing/applying.
7. Make right/left turns without rudder to show yaw.
8. Practice slow flight climbs, descents, turns.
9. Demonstrate flap extension/retraction at slow speeds to avoid stall.
11. Check altitude loss. Note airspeed loss in transition.
The stall is because of the angle of attack not the airspeed or attitude.
a. Mushy controls
b. Change in pitch of exterior air flow
c. Buffet, vibration, pitching, sounds
d. Stall warning
e. Body sensing
Natural Stall Warning
Some older aircraft do not have stall-warners. The natural stall warning is a first sensing of buffeting on the horizontal tail surfaces. The usual stall-warners alerts you up to 10 knots before the stall. The new FAR 23.207 requires prior warning but at no stated point.
At recognition reduce angle of attack. The quickness of the yoke movement should correspond with the abruptness of the stall. Apply smooth power and establish straight and level or climb as required. A pilot must make significantly incorrect control input during the stall to create an incipient spin. Instinctive reactions are invariably, if not wrong, too much control application. Stall and spin recoveries are intellectual; not instinctive.
A secondary stall is a 'failure' during any flight test. The secondary stall occurs when, during the recovery of an initial stall, the pilot over-controls the recovery. At the slow speeds involved there is greatly reduced stick forces. It all too easy to apply enough back pressure to make the secondary stall both abrupt and violent.
Stalls Down Low
There is something about ground proximity and low altitude turns that cause reactions leading to stalls. It could be that more attention is being paid to the ground than to flying. Many of the factors that are likely to increase stall speeds exist close to the ground. Turbulence, increased bank angle, lack of coordination, and low speeds are most likely.
The quality of the turn for a given angle of bank can make the turning stall either break ahead or create an abrupt wing break which if reacted to by aileron will only make things worse. The un-stalled wing aggravates the drop by providing ever more lift. The nose will drop while following the dropping wing. The ground makes the pilot reluctant to lower the nose, even though this is the only possible solution. If power is increased at the turn entry, the increase in speed may be used to offset drag created by the turn. Power applied while in the turn is already too late. Stall speeds increase as the square root of the load factor. A 30-degree bank results in only .15 G increase in load factor. Banks beyond 30-degree can result in dramatic load factor increases as can turbulence. An aircraft at low speed will stall at a relatively small angle of bank. When stalls occur down low there is usually insufficient altitude for recovery regardless of proficiency.
A deep stall can occur when the aircraft is in a very high angle-of-attack and high drag configuration as in minimum controllable. Airplanes, by design, will enter this undesirable mode only when loaded outside weight and center-of-gravity limits. Recovery from a deep stall may be possible only by changing the C. G. of the aircraft. Don't do stalls if you don't know the status of your C. G.
The deep stall occurs when the rearward center of gravity makes it so that the nose cannot be lowered with full elevator deflection. The stall angle of attack is exceeded by a margin well beyond the normal angle. The pitch-up is rapid and uncontrollable. The effectiveness of the horizontal stabilizer and elevator is dependent on the flow of the relative wind over these tail surfaces. The airflow over the tail surfaces is greatly reduced at slow speeds and high angles of attack. The nose will remain high with a very high rate of descent until the tail surfaces stall or until effectiveness can be restored. The use of full flaps can precipitate this condition in wind-shear conditions. T-tail aircraft are more prone, simply because there is no prop-wash to augment any relative wind needed to load the tail surfaces.
The better the stall recovery the less altitude lost provided a secondary stall does not occur. Excess forward elevator in recovery often leads to an excessive counter and the secondary stall. Any misuse of the aileron can give a sideslip leading to a spin. The inclinometer ball is the leading indicator of unbalanced flight. The lead sentence of this item is correct only if the stall is not prelude to a spin.
The amount of forward elevator must be referenced with the abruptness of the stall and the degree of pitch up acquired. The recovery initiated by the elevators must be correlated with the power/speed increases. Any turning motion should be corrected after speed has increased. Any bank should be controlled with the rudder only. Especially at high angles of attack. Spins result from improper stall recoveries and uncoordinated stalls. Power is not used if an incipient spin entry occurs.
When the root of the wing is stalled the disrupted flow of air over the wing affects the horizontal tail progressively as the stall progresses toward the wing tip. You will feel the vibration in the tail surfaces. Under the new PTS this is the time to initiate your recovery.
Flight instruction over the years has led to a gradual decrease in stall instruction and the complete demise of spin instruction. The fact that a stall is a prelude to a good landing seems to be beyond consideration. The stall is the point at which the smooth flow of air over the wing ceases to the extent that the aircraft is unable to sustain flight. This is the way to land an airplane. The stigma of the stall began because early aircraft lacked flight stability and stall predictability. Modern aircraft are, if anything, too stable for good instruction and too predictable in the stall. Every successive FAA test guide reduces the stall instruction required.
Early on in your training you performed basic stalls. Now that you are getting ready for the flight test you will perform proficiency stalls. Proficiency stalls are those stalls expected of the pilot applicants. Included in stall training will be such demonstration stalls as the accelerated stall and the oscillation stall which are not required except for flight instructor tests. Demonstration stalls are not part of the PTS but should be taught and demonstrated since they can occur when you least expect them.
One other thing that you might try is an oscillation stall to get used to really using the rudder. Begin like a straight-ahead power on stall with about 18-1900 rpm. Lift the nose slowly, very slowly until a stall occurs. The slow wing will always stall first. Do not correct by lowering the nose. Kick in full rudder to speed up the trailing wing and break the stall. This will cause the other wing to stall, kick in full opposite rudder. Do this rudder work rapidly before the plane can break into a spin. The rudder is your problem, not the stall.
Stall warners give a ten-knot warning of impending stalls as normally performed. The accidental inadvertent stalls that I have encountered occurred simultaneously with the warning. The real objective is not so much performance as recognition by sight, sound, and feel so that anticipatory corrections can be made. An imminent stall is a pre-stall condition that is recovered from before the actual stall occurs. Power alone may affect the recovery.
The amount of correction applied will vary with the aircraft and the abruptness of the stall entry. A gentle stall can be recovered gently. An abrupt stall requires a more positive recovery. Ground proximity can influence your reaction. (Understatement) Excessive negative load by excess force can delay the recovery. You want to reduce the angle of attack the minimum amount required. Recovery will require only that the nose be lowered to or slightly below the horizon.
A departure stall should be performed so that the bank is not allowed to exceed 20-degrees. This will require crossed controls. A departure stall that allows the bank to increase beyond 20-degrees has not corrected for the increased lift from the faster outside wing. Usually the pilot fails to apply sufficient rudder and the stall is climaxed by an abrupt wing drop which will be aggravated by the pilot trying to raise the wing with the stalled elevator. Voila' tout, a spin entry.
A full stall requires that an approach entry speed be used with power off and configured for landing. Once established raise the nose and hold heading with rudder. It can be performed in a constant 20-degree bank with coordinated rudder. Incorrect rudder results in abrupt wing-drop. Full stall occurs when the elevator is full back and up
Clearing turns. Carb heat and power smoothly off. Hold heading and altitude with yoke and rudder while aircraft decelerates. It is important that the yoke be pulled smoothly and logarithmically back and UP. (The unexpected sound of the stall warner often interrupts the students use of the yoke. It should not.) A technique for keeping the wings level is to maintain a constant heading on the heading indicator. Use the rudder. The first sign of stall is a slight tremor along the wing. This is the incipient stall. By bringing the yoke back and up still more a more violent tremor will we felt. This is the partial stall where the erratic airflow over the wings reaches back to vibrate off the tail planes. The tremor followed by a shudder, pitch and roll and nose or wing drop is a full stall. If the yoke is held back even through the nose or wing drop this is the aggravated stall. A spin will usually follow if rudder is applied so as to lose directional control.
There are several common faults associated with the power off stall. Most students have been influenced by certain texts into scaring themselves doing the stall. They pull back too quickly and push forward abruptly. If the yoke is brought back The violence of stall recovery is proportional to the abruptness of the stall. The more gentle the stall entry attained by holding altitude and attitude the more gentle will be the stall.
Recovery is initiated by lowering the nose to or slightly below the horizon, applying full power, leveling the wings as required, removing any flaps and initiating a climb. Properly performed power off stalls should be recovered with a loss of about 100' before a positive climb rate is achieved.
A gentle entry to the stall can be followed by a smooth gentle recovery. Where the wing begins its stall at the wing root the turbulence makes it possible to feel the turbulence vibration as it affects the horizontal tail surfaces. Some students sense this as the stall, whereas it is an incipient phase likely to be followed by the tip stall. The abrupt wing drop occurs with a tip stall where rudder is not applied to cause both tips to stall at the same time. It ideal stall break is straight ahead. It can only be achieved when the rudder is properly used.
A variation of the power off stall is sometimes called a 'characteristic stall'. In this instance the stall is performed with the power off but the recovery is also accomplished with power off. This is the stall situation that would occur where an engine failure exists and the pilot tries to stretch the glide.
For propeller-driven aircraft it makes a difference; with power off stalling speed is somewhat below the power-on stalling speed, because with power on the speed of the air just behind the propeller is above the IAS. So for a given angle of attack there is a somewhat greater lift with power on.
Clearing turns, CH, power 1500, hold heading and altitude while slowing to 60-kts. Power 2000 rpm or full, hold heading with rudder as plane climbs and slows. Increase back and up pressure until stall, relax pressure and allow nose to fall to or slightly below horizon. Full power and climb at 65-kts. With power at 1300 RPM this stall is used in making full flaps soft field landing.
Recovery is made by lowering the nose to or slightly below the horizon and at the same time applying full power and rudder to maintain heading. Level the wings and initiate a Vy climb.
Density Altitude Recovery:
Lowering the nose to or slightly below the horizon makes the recovery and power is NOT changed while an effort is made to climb. This demonstrates the very real problem of a departure stall made at altitude where additional power may not be available.
First you must know what you are trying to simulate. Visualize a situation where you have just reached rotation speed when a stopped gasoline truck pulls on to the runway about 500 feet a head of you. Without thinking, you will pull back on the yoke and turn to go over and avoid the truck.
Preliminary exercise is to go into slow flight. Look down the leading edge of the left wing and hit the right rudder. You will see the leading edge speed up. Relax the rudder and it will fall back. One wing, the slowest wing, will stall first any time the wings are not 'flying' at the same speed. Now you know why the wing drops and how to stop it.
An additional exercise is to slow to 60 knots with power at ~1900 rpm. Very slowly raise the nose to the stall. Hold heading with rudder. make recovery only by lowering the nose to or very slightly below the horizon. Do not change power as with normal recovery. Leave the power alone and do a series of stalls one after the other. You should be able to enter the stalls and make the recovery within 100 feet of altitude. If a wing drops, raise it with rudder not yoke.
In this particular stall a series of them can be made within a 100' altitude range just be making a smooth recovery and then slowly enter the stall again. Leave the power alone. Doing several of these will make you more aware of the variable rudder force changes required to get a smooth stall break without wing drop. A rudder exercise can be performed while doing this stall. You can perform an oscillation stall by 'walking" the rudder to bring up any wing that drops. How far into the stall you are will determine the amount of rudder input required. In the introduction to this the student should be shown that application of right rudder causes the left wing to move forward. The trailing wing will always stall first. Ailerons should be neutral.
When you have solved the rudder problem you can go to banks. Banks should not exceed 20 degrees regardless of power. The step by step additions of power in 200 rpm increments should proceed as before until you get to full power. The geometry of your arm and hand on the yoke in all stalls is important. You should be able to pull and LIFT the yoke with only two fingers. This will help you avoid increasing any bank beyond 20 degrees. If you are flying and using a full grip on the yoke...stop it now.
I have, for years, used this stall as a confidence maneuver for students. With power at 2000 and kept there, a repeated series of stalls can be performed within 100 feet of altitude. Student just lowers nose to regain flying speed that then enters another stall. Misuse of the rudder causes a wing to drop. Then the wing must be raised only after the nose is lowered and flying speed regained. The cause of a wing dropping can be shown by observing the leading edge of a wing as it reacts to rudder application. Whenever a wing has dropped in stall, the stall should be repeated with corrective rudder applied.
First step is to slow the aircraft down at altitude. there would be nothing wrong to getting down to 55 knots or even 50 knots. The slower you go the less the nose will pitch up. Since rudder seems to be a problem you should practice with less than full power more than a few times. Begin with only 2000 rpm until you get the rudder so that you break straight ahead. Do the first series straight ahead with no turns. the higher the nose and power the more rudder. Keep the heading indicator still with the rudder and your wings will be level. Try some of these under the hood.
Clearing turns, CH, power 1500, hold heading and altitude while slowing to 60 kts. Power 2000 rpm or full, enter 20 degree bank as plane climbs and slows. Increase back pressure until stall. If done properly nose will fall forward. Wing drop or yaw indicates improper use of rudder. At stall lower nose to or slightly below horizon, level wings while applying power, raise nose, climb at 65-kts. This stall is best avoided by maintaining correct climb speed and never banking over 30 degrees in the pattern.
This stall is best avoided by maintaining approach speed and limiting banks to 30 degrees. Failure to maintain ground-track in reference to runway and wind effect is a common cause leading to this stall situation.
Clearing turns, CH, power 1500, at white arc put in full flaps while holding heading, altitude and maintaining airspeed at 60-kts. If done correctly full flaps and 60-kts occur simultaneously. Enter 20 degree bank and hold altitude until stall.
If nose properly falls forward, apply full power and raise flaps 20 degrees. Initiate climb at 65 kts and bring up rest of flaps. The yoke pressures change continuously from forward to back as the flaps are removed. Wing drop is indicative of improper rudder pressure.
(No longer FAA required but exposure needed.)
There is an airspeed at which a wing will stall at 1 g in level flight. This is calculated at gross weight using an airspeed selected by the manufacturer. You will find this at the bottom of the green arc on the ASI (Vs1) . With gear and flaps the bottom of the white arc is Vso. The accelerated stall is a stall that occurs at a wing loading over 1 g.
There is a portion of any airplane's flight envelope where the addition of a load factor above 1 g will produce a stall at a higher airspeed than Vs1 and not hurt the airplane. You will find this portion of the flight envelope between Vs1 and Va, which is the maneuvering speed for that airplane. Within this area we can define the accelerated stall. Not above Va, because above Va, structural damage to the airplane has occurred before the accelerated stall has occurred.
The one common denominator in all stalls is the critical angle of attack. Every stall is a function of angle of attack and not airspeed or load factor, even though these factors are present in the accelerated stall. You can stall an airplane at various airspeeds and load factors, but at only one angle of attack. Angle of attack is the key to understanding stall, especially the accelerated stall.
This stall is unique in that the ailerons are used for the recovery. It is
called accelerated because the stall occurs at relatively high speeds while
the aircraft is subject to greater than normal G-forces. The factor that
causes this is the high wing loading due to a steep bank. Any steep bank with
abrupt yoke pressure to hold altitude can lead to this stall.
Make clearing turns at cruise. Enter a 45 degree steep bank at level altitude and cruise speed. Hold that altitude and bank while applying carburetor head and smoothly-gradually reduce power to OFF. Increase back pressure to prevent ANY loss of altitude. If the back pressure is abruptly applied any stall will be rapid and severe. If VSI goes down you will go down shortly thereafter. It this happens, start procedure over again. Yoke must come full back and up to get stall. The resulting centrifugal forces will increase the wing loading. The plane will stall at a higher speed because of the excessive maneuvering loads. Any descent will void entire procedure. Practice at altitude and keep your turns coordinated
If you have the yoke all the way back and the power is off, you have done as much as you can to make it stall. Try doing the maneuver a bit faster and you may get the break you are looking for. This stall is unique in that the ailerons remain effective so it can be quickly broken just be leveling the wings.
Since stall occurs at a higher speed, ailerons will still be effective and recovery may be initiated by leveling wings and using rudder. The accidental entry can occur from any steep bank done with abrupt yoke pressure while endeavoring to hold altitude. This is the only stall that does not require the nose to be lowered and in which the ailerons remain effective. Failure to initiate stall recovery can result in a power-on spin. Uncoordinated rudder will give a spin entry. (see spins)
My personal belief is that this particular stall should have remained as part of the PTS because of the smoothness required for proper performance and recovery. This is the stall that is apt to occur when you are turning base to final and you have over-shot the runway. You increase the bank angle and pull back on the yoke to hold the nose up. The g-load increases and you do not have altitude to recover if a spin results. The difference here has to do with the use of rudder and existence of yaw. Uncoordinated you get the spin entry, coordinated you get an accelerated stall.
I suggest that you limit your practice of this stall if you are subject to hemorrhoids.
The real value in learning accelerated stalls is that no other maneuver so clearly illustrates to the student the relationship between angle of attack and the stall. Simply performing stalls with no loading caused pilots to incorrectly relate stall to airspeed and not attitude..
The accelerated stall is sometimes called the 'moose stall' since it often occurs when Alaskan pilots attempt to circle a moose. The steep turn, low altitude, inattention, distraction, abrupt control movement when mixed with ignorance and overconfidence.
The accelerated stall, correctly performed below Va and accompanied by a complete explanation by a competent instructor, leaves no doubt whatever in the mind of the student that any airplane can be stalled at any airspeed and at any angle of flight, if critical angel of attack is reached.
To unload the wing you "step on the blue" along with forward yoke to break the stall and lower the load factor. Then use top rudder to initiate the recovery. Very often in an unusual attitude, the pilot will pull back on the yoke. The unusual attitude requires that the angle of attack be lowered and the stall broken. It is the instinctive response to the unusual attitude that makes breaking the stall difficult to achieve. Attempting to level the wings with the ailerons will produce extreme attitude changes unless the stall is broken first.
If the aircraft is trimmed for an approach speed, a spiral dive derived from an unusual attitude may increase the speed so that leveling the wings will tear the aircraft apart. Excessive load must be reduced by pushing forward on the yoke.
Control Turn Base to Final Stall
The cross-control stall occurs when the pilot reacts to a high ground speed due to a tailwind as indicative of a need to reduce airspeed while on base. This sensed need for speed reduction occurs just after the pilot notices a turn is required. Then the pilot realizes that the turn cannot be completed in a normal bank so more rudder is used to speed up the turn. This then requires 'up' elevator to keep the nose from dropping.. This slows the aircraft even more and the lower wing stalls and tucks under and straight down. With less than a few hundred feet of altitude, no recovery is possible.
This entire cross-control scenario can be avoided by planning to fly any
downwind leg that is being blown into the runway at twice the distance away
from the runway as a normal downwind. The benefit compounds by giving a longer
base leg with more time to plan and make the turn to final. It is too bad,
even sad, that the FAA landing booklets only address the problem in their
presentation diagrams. What is needed is a few solutions diagrams that show
how the situation can be avoided.
Things that can help deflect the situation:
1. Diagram the ATIS or AWOS to show both the runway and the wind velocity/direction vector. This will dramatically show when the need for a wider downwind leg is required.
2. At a controlled airport you have the option to request a pattern that gives a headwind rather than a tailwind on base. The aggravated cross-control stall uses full right aileron and full left rudder will be totally uncoordinated. The use of full power into this stall will cause the aircraft l to snap over in a New York Minute. Aircraft will go inverted if the stall is not broken immediately.
The deadliest stall is the cross-control stall that occurs in the landing
pattern during a turn from base to final. The precipitating factor in the
stall is in a tailwind on the base leg. The pilot may have failed to
adequately correct for the crosswind on the downwind leg. The aircraft has
drifted into the runway. This makes the base leg not only short but relatively
fast. The speed both real and by illusion may cause the pilot to overrun the
final approach course, raise the nose to reduce the speed, make a steeper than
normal bank, or worse add top rudder to get the nose around more quickly. The
slightest inattention or distraction will not catch the resultant nose drop,
stall, and the snap roll toward the low wing will be an unrecoverable spin
entry due to lack of altitude. Although the recovery may be impossible, the
prevention lies in awareness as to how crosswinds tend to reduce the base leg.
With the awareness comes flying a pattern flight path that will give a longer
leg which, even at a higher speed, will allow a planned normal turn to the
final approach course.
I am fortunate in having double-dual runways at my home field. This means that in strong crosswinds I am able to demonstrate and practice cross-wind landings in both directions. This means that the student will experience having to crab into and away from the runway to compensate for the wind effect on the base leg and base-leg turn to final.
#1 Usually results from a skidding turn to final where the pilot overshoots of final makes a steeper bank, uses too little rudder, nose goes down, and sink rate increases. The pilot tries to raise the nose with elevator. You have an accelerated stall, spin, and crash. This stall/spin is major fatality problem because it occurs too low to make a spin recovery possible.
The skidding turn, ball to the outside of the turn, is the opening for a spin. NEVER use the rudder to increase the turn rate. The uncoordinated turn is region where this stall and spin accident occurs. In crosswinds that are blowing you into the runway double your perception of the usual distance away from the runway.
#2 Aircraft is close to ground so pilot is reluctant to lower wing into bank. Instead tries to execute turn using excessive rudder. Excess rudder causes plane to bank into the turn and the nose to pitch down. Pilot applies opposite aileron to raise wing and nose up elevator. Attempting to raise a 'dropped' wing by applying opposite aileron increases the effective angle of attack and will induce or aggravate a stall. Inside wing will drop and roll aircraft inverted after accelerated stall.
Fly the correct altitude, pattern size and airspeed for the wind conditions and you will not have a problem.
The base turn in a following crosswind creates a problem with holding airspeed. This turn makes the existing crosswind into a tailwind and the pilot's peripheral vision will detect an increase in ground speed. If the turn makes the existing crosswind into a headwind the eye will detect a decrease in ground speed. This conscious or unconscious perception of speed may and often does cause the pilot to make unintentional changes in the airspeed. A constant airspeed is essential for all landings.
The base leg perception of ground speed and maintenance of a single indicated air speed (IAS) is essential for making the turn to final. If wind, illusion, or inattention positions your plane too close to the runway on downwind your base leg will be short. This most often occurs at night and at small unfamiliar fields. Students will turn too early with the headwind and too late with the tailwind. Being too late means that the student has overshot alignment with the runway. The result is that procedures become hurried and airspeed un-stabilized. Both these problems are made worse if the downwind leg is flown to give a short base leg. The dangerous part of this is that the pilot may have slowed below the proper airspeed. Normal reaction to overshooting is to make the turn steeper to regain alignment. The combination of slow and steep is the introduction of a stall spin accident. Abort the approach and GO-AROUND. Never exceed a 30 degree bank in the pattern and use sound as indicative of airspeed changes.
A high proportion of accidents seem to result from these improperly performed turns at low altitudes. Low airspeeds combined with steep turns result in stress and instinctive reactions. I would think that the mere factor of ground presence causes excessive distraction. The making of turns at low altitudes is not a common general aviation procedure. The distraction of rapidly moving ground at unfamiliar angles is unavoidable. There are illusions which result in inappropriate control application. The nose will always drop toward the low wing.
The pilot who normally flies solo or at less than gross weights must be
prepared for higher stall speeds and load factors when fully loaded. As a
reminder a 20% increase in weight will give a 10% increase in stall speed. The
combination of all factors result in an unexpected stall followed by a spin
entry. The usually safe 30 degree bank can give a 50% higher stall speed if it
is performed in moderate turbulence. Most of our low level turns in training
are performed at much less than gross weights. Once out of training our
aircraft weights get much closer to gross.
Now we have set the scenario for a stall spin accident that beings at low altitude. Wings tend to stall always at the same angle of attack. We can increase the load factor by making a steeper bank. Being at gross weight frames the picture. Gross weight, higher load factor and at the stall angle of attack. Now comes the surprise. Add just one good shot of turbulence. The stall onset arrives and it happens at a much higher airspeed. The pilot has never stalled at such a high speed before. The pilot feels deceived by his plane and instruction in the final moments. It was not supposed to happen this way.
The elevator trim stall is illustrative of what can happen when full power is applied for a go-around with full nose-up trim. Full power application under such conditions can cause abrupt pitch up such that any rudder use may provide a spin entry, surprise and over-power the pilot's ability to hold the yoke forward. Can be prevented if sufficient control force is applied to prevent pitch up before clean up. A pilot who does not keep track of his trim can get into stall trouble. Sudden application of power with pilot not expecting need for extra right rudder application due to P-factor .
Landing approach configuration trimmed for speed. Partial power with little elevator or rudder pressure +distraction. The stall is initiated with partial power partial to full flaps and trimmed for approach speed. When full power is applied the nose will pitch high and to the left.
If the pilot does not counter the forces and remove the trim he can be physically overcome. In an actual go-around situation the altitude loss required could be below ground level. (understatement) At stall, recover to normal climb. Stress attitude, control pressures, and trim during go round.
While in full flap stall with full flap attempted climb. likely secondary stall. Full flap stall with rapid removal of flaps to produce secondary stall. Accidents occur most often by failure to initiate go-around before ground obstacles become a factor.
To simulate an accidental stall the instructor must get the student totally focused on an unrelated factor. The easiest factor is altitude. Demand that throughout the following maneuver that the altitude must not be allowed to vary. Heading may be used alone or in conjunction with altitude as the concentration factor. Eliminate an essential element from being able to hold altitude (power) or heading (rudder). The clock can be used as a focus item as by having the student call out the number of seconds every seven seconds or even every four seconds. What we are doing is setting up a mental set that eliminates flying the aircraft as a factor. Now we can get the accidental stall.
Regardless of the stall type being performed, it is vital that the rudder be used during entry and recovery. In the absence of yaw a spin will not occur.
Engine Failure at Altitude Stall
As always, clearing turns. Carburetor heat and power to idle. Retain altitude and turn immediately toward possible landing area. Trim for best glide speed. If in doubt trim all the way back. Use your checklist. Make your field selection early and stay with your choice.
Changing your mind should be only as a last resort. If you have some power available you can approach at a lower touch down speed. Flaps only when field is certain. You and the aircraft can bear horizontal impact better than vertical impact. An impact below 45 knots is both survivable and likely non-injury.
Takeoff Engine Failure Stall
The standard emergency for engine failure on takeoff is to land ahead into the wind. Make no more than 30 degrees of heading change to locate the best landing place. An emergency landing into a 10 kt wind at a full flap stall speed of 35 kts gives you a survivable ground contact speed of 25 kts. However, there is another option possible if sufficient altitude has been gained before failure. (A good reason to always takeoff and climb at best rate, Vy) To determine this altitude it is necessary to practice at altitude.
At altitude initiate climb at best angle of climb (Vx) on a North heading, pull power and hold pitch attitude to simulate engine failure. Repeat exercise but lower nose to get best glide speed. Have the student execute a right turn in a 30 degree bank to 240 degrees. Note the altitude loss. Do the same 240 degree turn to the left. Note the altitude loss. Now do both turns with 45 to 60 degree banks. and note altitude lost. Add 50% to the altitudes as a fudge factor for actual use. From these turns you should decide that the steep turn loses the least altitude. Having determined this we now can add some factors for returning to a runway. If there is any crosswind always make the turn into the wind since it will bring you back to the runway. If there are parallel runways turn to the parallel since only 180 degrees of turn will be needed. Crossing runways may even need less turn. Consider a crossing taxiway.
If the tailwind is 10 kts it will double the required runway for landing. If takeoff is into relatively strong head wind the ground speed of the turn will increase dramatically. The increased ground speed decreases the time available to complete the turn. Turn errors multiply if the pilot slows the aircraft in an effort to slow the ground speed.
Instinctive and most likely fatally incorrect effort is to turn back. Lower nose to best glide attitude. Landing attitude under control assures survivable ground contact. This is the best 'every time' solution until you have determined your personal 'turn back' limits with a fudge factor.
Engine Failure on Final Stall
There is always an instinctive effort to maintain 'correct' relationship of runway to nose of aircraft. Desire to keep from losing altitude.
Simulate power loss on final in full flap landing configuration. Student is to avoid losing over 100 feet in next 20 seconds while calling out every five seconds on clock. Using elevators to keep from losing altitude for 20-30 seconds. Stretching glide fails as ever increasing pitch results in stall as aircraft runs out of airspeed and altitude at the same time.
Bring up all flaps to extend glide. Maintain glide speed. No heading changes beyond 30 degrees. Accept altitude loss while bringing up flaps. Fly in ground effect. Trim.
The correct procedure for this can be easily practiced. On short final at about 400', simulate the loss of power, have the student immediately remove all flaps while maintaining approach speed. Accept the immediate loss of altitude as it is traded off for up to 1/2 mile of glide range. Try it.
Landing Flare Stall
There are pilots who use trim is make the flare to landing. This is a trim practice not uncommon among Piper pilots. Piper's become quite heavy in the flare and pilots often use trim to ease the load. An aircraft trimmed in this manner during a go-around can give an extreme nose-high pitch attitude and a stall or spin. This is especially true in higher powered aircraft. This should be simulated only at altitude. It is, also, an excellent demonstration that the application of only power causes a decrease in airspeed
When level but at a pitch attitude beyond the stall angle of attack, any movement along the roll axis will make the rising (outboard) wing to decrease its angle of attack while the descending (inboard) wing will increase its angle of attack. The rolling and turning of the aircraft is caused by the differing lift and drag of the two wings. Encountering a cross wind when trimmed for short field approach while not applying enough forward yoke pressure to maintain airspeed during the 1/2 Dutch roll cross control descent.
Enter into fully trimmed slow flight both with and without flaps. Demand that your student immediately slow an additional 10 kts due to imaginary intruding traffic. Or, have student do this while getting a pencil from between his feet. Distract, give problems which will cause student to enter stall situation.
Initiate go-around immediately. Lower nose and get into ground effect while applying full power. If the nose-wheel hits continue the go-around and avoid moving the yoke from level flight position. (See nose-wheel landings)
Premature Flap Retraction Stall
Initiated at altitude from full flaps descent and level off to below full flap stall speed. Apply full power and make most rapid retraction of flaps. Results in full/partial stall. In a steep climb. The use of right aileron and no rudder to keep the flight path straight will cause a spin entry. The left wing will drop and roll, the power will give yaw and a left spin is entered without the use of rudder.
Milk flaps at least half of flaps off on any go-around until Vx is reached and climb initiated.
Go-Around in a Right
Simulate slipping approach to the right with proper airspeed and trim. Right aileron and left rudder. Full power go-around and set pitch without neutralizing rudder.
Don't leave level attitude in go-around until control and airspeed are obtained.
Slow Flight in Pattern Stall
Attention diverted from flying to traffic. This may result in loss of altitude on downwind and a corresponding low-altitude base leg turn.
In simulated traffic pattern at altitude, reduce power and increase pitch. Continue to slow down and increase pitch then create diversion of attention to prevent notice of near stall condition.
Lower nose, trade altitude for speed if necessary. Full power. Clean up and go-around.
Short Field Takeoff Stall
The short field takeoff requires that the pilot set the pitch attitude so that the POH Vx speed will allow the aircraft to perform at its maximum level for obstacle clearance. Pilot control must be positive, precise, and coordinated.
Premature rotation before Vx with inadequate rudder control. Insufficient rudder often cause aileron use to create a slipping turn to the right. From right turn stall/spin caused by excessive right aileron. At stall spin is very abrupt, "over the top", and to the left. From left turn 'P-factor" gives nearly correct coordination and spin entry is slower.
Abrupt lowering of the nose to trade any altitude for airspeed. Full power. Get into ground-effect. Get speed before climbing. Abort if space permits.
Falling Leaf Stall
You can do a falling leaf stall by doing a straight-ahead power-on stall and hold the nose straight by using the rudder to prevent wing-drop. This is a great rudder exercise and confidence builder.
More on Stalls
Ground school and flight school presentations of stalls are defensive measures and both act as stall awareness insurance. The instructional purpose of these stalls is to emphasize the importance of maintaining coordination in takeoffs and landings. The total actual stall performance time probably does not exceed 30 minutes for any given pilot. This would indicate that we do not spend enough time refining the stall prevention/recover reflex. After certification very little review of the stall phases occurs. Flights seldom include any stall awareness practice.
Best awareness review is to set up stall situation where an uncoordinated rudder condition will exist. The critical angle of attack can be exceeded from any flight condition. Even the nose below the horizon can cause the wing to exceed the critical angle of attack.
One practice exercise of the stall can be directed toward the endurance speed of the airplane. At altitude reduce power while holding altitude and a Vref indicated airspeed which can be maintained at the lowest power. Once the minimum power and speed combination that maintains altitude has been attained, you are at the endurance speed/minimum sink speed. The minimum sink speed is a glide speed that, through the use of power can be used to exceed any maximum glide range. Trim for hands-off.
From this configuration lower the nose slightly and wait for the plane to recover back to its level flight condition. Next apply back pressure to lower the speed by up to 10 knots and hold the airspeed constant with only yoke pressure. After an initial climb the aircraft will begin to lose altitude. You have placed the aircraft 'behind the power curve' for this particular configuration. The nose must be lowered for any recovery to be possible. This same procedure can be configured for full power operation with the nose so high that altitude is barely maintained. Any additional raising of the nose will cause a descent even with full power. Induced drag is greater than any lowering of parasitic drag. Only a lowering of the nose and a loss of altitude will permit a return to normal flight.
Any flight in this area of reversed command requires the pilot to recognize the condition and do the exact opposite to what works on the front side of the power curve. The most common occurrence of the reversed command situation occurs when the pilot uses yoke and power in combination of a constantly decelerating landing approach. From a slightly low long final a bit of power is used to raise the nose. After a few seconds the apparent glide path again becomes slightly low. A bit more power is added for another apparent correction. What is not noted, is that the airspeed has dropped with every bit of additional power. This time the plane drops more quickly below the glide path. More power is added to maintain the glide path but now the power increase does not solve the glide path problem. You are now in the area of reverse command and only a lowering of the nose will resolve the problem. The determining factor now becomes one of available altitude. With available altitude a recovery is possible by lowering the nose. Without available altitude no recovery is possible. This is why, any time you are low on the approach glide path, an application of full power while retaining airspeed is the best, safest, and only appropriate correction. Power for altitude, pitch for airspeed rides again.
If a pilot can avoid those distractions caused by not keeping ahead of the airplane he has eliminated most of the precipitating causes of accidental stalls. Once out of those woods, however, you must watch for a alligators hiding in the grass. Those little surprises that always occur at the most inappropriate moments. These distractions will affect your aircraft control over speed, altitude, and heading. Any distraction be it malfunction, traffic, or radio that reduces basic aircraft control is a probable cause for an accidental stall. An abrupt full stall can put your nose straight down. Even then, your trained reflex should make you put the yoke forward to break the stall. Panic reactions in crises situations are more likely to kill you than trained reflex.
Stall spin accidents are still occurring at a rate of one-per-day as they have for many years. The cause is usually a distraction, followed by lack of recognition which is followed by delayed recovery. Delayed recovery is usually due to instinctive rather than trained reactions to seeing the ground over the nose. Instincts will inhibit recovery action. The hazards of unintentional stalls can be avoided by:
1. Avoidance of low and slow flight.
2. Limiting pattern banks to 30-degrees
3. Keeping some power on until just before touchdown.
4. Keeping your hand on the throttle
5. Using carburetor heat prior to power reduction.
6. Avoiding a pitch attitude that covers the horizon.
7. Don't look backwards to see the ground.
8. Always fly with a trimmed airplane.
8.5 When distracted, you should be able to fly the plane with rudder alone, no hands.
9. Don't carry on conversations during critical flight maneuvers.
10. Let discrepancies wait for resolution on the ground.
Ask a student how high the nose is above the horizon when practicing stalls and the handee you get will be between 20 and 30 degrees. Fact is it is less than half that without flaps and very near level when with full flaps. No flap power-on stalls will be less than 15 degrees unless entered at higher speeds. The usual stall attitude is the same as when a tail-wheel aircraft sits on level ground.
At altitude slow to 1.5 of clean stall speed and do some turns at 30-degree while holding altitude. Now, reduce the speed by 10 knots and do the same. Notice the change in control feel and response. Try it again still slower and note that only by the addition of power can you maintain altitude and that little margin above stall remains. Learn the sounds and feel of near-stall flight.
Stalls in Brief
POWER-OFF STALL........ POWER-ON STALL ........DEPARTURE STALL
CLEARING TURNS ..........CLEARING TURNS......... CLEARING TURNS
CARB HEAT ......................CARB HEAT .....................CARB HEAT
PWR TO OFF ....................PWR TO 1500 ...................PWR TO 1500 HOLD
HDG. & ALT..................... HOLD HDG. & ALT. .........HOLD HDG. & ALT.
R-RUDDER AS REQD.......R-RUDDER AS REQD ......R-RUDDER AS REQD.
BUFFET OR STALL .........SLOW TO 55 KTS ............SLOW TO 55 KTS
YOKE RELAX ..................FWARD PWR UP ............. PWR UP 2000/FULL
NOSE TO/BLOW HRIZN R-RUDDER ........................20 DEGREES-CENTER BALL LEVEL WINGS
BUFFET OR STALL .........BUFFET OR STALL ..........FULL POWER-CLIMB 65 KTS
YOKE FORWARD ...........YOKE FORWARD ............YOKE FORWARD
R-RUDDER/HOLD HDG. .NOSE TO/BELOW HRIZN NOSE TO/BELOW HORIZON
LEVEL WINGS .................LEVEL WINGS ..................LEVEL WINGS
F-POWER-CLIMB ...........65K F-POWER-CLIMB .....65K CLIMB
R-RUDDER FOR HDG. ....R-RUDDER TO HOLD HDG.
APPROACH STALL............... .....ACCELERATED STALL ..........FULL FLAP GO-AROUND
CLEARING TURNS .....................CLEARING TURNS ................FULL POWERCARB HEAT
......................................................45 DEGREE STEEP TURN ......HOLD NOSE LEVEL
PWR TO 1500 CARB HEAT/.......YOKE BACK R-RUDDER-......HOLD HDG.
HOLD HDG. & ALT. ...................REDUCE PWR/YOKE BACK...FLAPS UP 20
WHITE ARC REDUCE PWR/......YOKE BACK........................... .MILK BELOW 50KTS
FULL FLAPS REDUCE PWR/.....YOKE BACK 60-65 KTS.........HOLD HDG. & ALT.
PWR OFF/.....................................YOKE FULL BACK... .............FLAPS UP20 DEGREE ........
.L-R BANK ..................................IF ANY LOSS OF ALT.
CLIMBHOLD ALTITUDE ...........START OVER R-RUDDER-......HOLD HDG.
BUFFET OR STALL BUFFET OR STALL
YOKE FORWARD .....................USE AILERONS TO LEVEL......
LEVEL WINGS FULL POWER
FULL POWER R-RUDDER TO HOLD HDG.
FLAPS UP TO 20 DEGREES (Not FAA required)
CLIMB SPEED 60-65 KTS
CLIMB 65 KTS
R-RUDDER TO HOLD HDG.
Stall strips are put on the leading edge of an aircraft wing is designed and placed to prevent an abrupt wing-tip stall, but instead to allow any stall to move gradually out from the fuselage to the wing tip. The stall strip's purpose is to cause a stall before any part of the outboard part of the wing stalls. This means a decreased abruptness of any wing drop.
Is a stall coordinated?
Depends on your definition of "completely coordinated".
I doubt that ‘perfectly coordinated’ ever occurs except in a passing moment. Having the ball centered in a stall still has a slight margin for error. Parallax exists. That said...
The degree of precision in any stall is determined by how the nose drops at the stall. Even in a departure stall with power and a 20-degree bank the coordinated stall will have both wings dropping evenly with no tucking or dipping.
When a student of mine drops a wing during such a stall, I use it as an opportunity to demonstrate rudder power.
Slow the plane to a speed approaching clean stall and allow some lack of coordination to occur. This means that one wing will start dropping. Have the student use only rudder to bring the wing up. Keep the banks less than 15-degrees and use only the rudder, no yoke movement at all to keep the wings level., just rudder.
A bit more squirrelly in Cherokees but an important rudder skill practice along with Dutch rolls.Return to whittsflying Home page