Basic Pilot Quiz 2 – Rudder Usage
Some of the most common weaknesses noted among pilots include improper use of the rudder and lack of rudder usage. In a stalled condition, this can lead to an unintentional spin. Lack of proper rudder use can mean more drag and less flight efficiency and some discomfort for the passengers. Poor rudder coordination can also make training maneuvers more difficult and cause them to turn out wrong. Correct and precise rudder application is essential to performing aerobatic maneuvers properly.Here are some questions on the application of rudder in some basic scenarios. It is assumed that the student or pilot taking this test has a good understanding of the terms P-Factor, Torque effect, Slipstream Effect, Gyro Precession and Adverse Aileron Yaw. If you are not familiar with these terms or their application, you may want to refer to the FAA’s Pilot Handbook of Aeronautical knowledge or schedule some ground tutoring with Steve. Posted 05-26-2015 by Steve Shaner.
Assume in each of these situations that you are flying in a typical single engine airplane with the propeller turning clockwise as viewed from the cockpit and the airplane is rigged properly. If the airplane has rudder trim, it is set to neutral. The airplane has tricycle landing gear which is not able to caster for crosswinds. Smooth, gentle control applications are being used.
1. You are in cruise straight and level flight when you experience a complete engine failure. What rudder application will be needed during your glide straight ahead?
A) Add right rudder B) Add left rudder C) Leave the rudder neutral
2. On take off roll, you are holding right rudder application to stay on the centerline with no crosswind. Now you pitch the nose up in rotation. What rudder application will be needed after the nose wheel lifts off the ground?
A) Keep the same amount of right rudder in B) Neutralize the rudder C) Add more right rudder D) Add left rudder
3. While practicing a full-power takeoff and departure stall (power-on stall), you are in a steep nose up attitude with full power and right rudder and you begin recovering by lowering the nose. What rudder application will be needed as you are lowering the nose?
A) Keep the same amount of right rudder in B) Relax rudder to neutral C) Add more right rudder D) Add left rudder
4. You are in a right climbing turn with full power and right rudder applied. You begin rolling left to return to wings level, remaining in the climb. During this rollout, what rudder application will be needed?
A) Add left rudder B) Add more right rudder C) Neutralize the rudder D) Use less right rudder
5. You are established in a coordinated 45 degree bank steep left turn, maintaining a constant altitude. What rudder application will be needed?
A) Hold left rudder B) Keep the rudder neutral C) Hold right rudder D) Adjust the rudder as necessary to keep the nose at the right height on the horizon
6. You are making a landing with a strong crosswind from the right. You are in a side slip attitude with the nose straight in line with the runway centerline, about to touch down. what rudder application will be needed at this point?
A) Hold right rudder B) Hold neutral rudder C) Hold left rudder D) Adjust the rudder as necessary to keep the airplane over the centerline
Here are a couple of questions for Commercial Pilot students:
7. In the last half of the turn in a chandelle, which turn direction requires the most right rudder?
A) Chandelle to the left B) Chandelle to the right
8. In a Lazy-8 maneuver, which segment of the maneuver requires the most right rudder?
A) In the right turn from 0 degrees to 45 degrees of turn B) In the left turn from 45 degrees to 90 degrees of turn C) In the right turn from 45 degrees to 90 degrees of turn
D) In the left turn from 135 degrees to 180 degrees of turn E) None of the above
The answers are shown below
1. B Most single engine airplanes have structural design features that cancel the left turning or yawing tendencies of torque effect and slipstream effect in straight and level, normal cruise flight. These features may include an offset vertical stabilizer, a left wing mounted at a slightly different angle of incidence, an engine mounted with the front slightly crooked to the right or a left flap at a slightly lower angle than the right flap. When the engine fails or is retarded to idle at cruise airspeed, most of the torque effect and slipstream effect is lost, so these design features go unopposed and can cause a slight right yawing tendency. The bigger the plane, engine and propeller, the stronger this tendency will be. A Cessna 150 may need very little left rudder after an engine failure while a Piper Saratoga will need significantly more.
2. C During the take off roll, you are holding right rudder pedal pressure to offset the left turning tendency caused by torque effect and slipstream effect. This is accomplished by steering the nose wheel to the right (if equipped with a steerable nose wheel) and applying right rudder deflection. When you rotate or pitch up on the takeoff roll, you now have added P-Factor or Propeller Factor to the aerodynamics, so you have 3 left-turning forces to compensate for instead of 2. You have also lost the steering assistance from the steerable nose wheel (if equipped), so all of the work is now being done with the rudder, so you will now have to add more right rudder deflection.
3. C At the point of stalling power on, you are holding right rudder for torque effect, slipstream effect and p-factor. As you are lowering the nose, you induce a 4th left-turning force, which is gyro precession with regard to the propeller acting as a gyro. This will require that you add more right rudder until you finish lowering the nose. After this, you will need significantly less right rudder as you have now eliminated gyro precession and p-factor, if the nose is at or below the horizon.
4. D If you roll somewhat aggressively to the left, than C would be the correct answer. As you are climbing, established in a left or right turn or wings level, you will be holding right rudder to compensate for the left yawing tendency caused by torque effect, p-factor and slipstream effect. When you roll to the left in a climbing turn, you induce adverse aileron yaw, which produces a right yawing tendency. Since the 3 left yawing tendencies are still at play, they would normally cancel out and over power the adverse aileron yaw somewhat. This results in the need to only reduce the right rudder being held. When the left rolling is stopped, then the adverse aileron yaw disappears and you would need to increase the right rudder application back to the original amount to compensate for the 3 other left- yawing forces.
5. B Once established in a level, coordinated turn, there are no turning forces that need to be compensated for. The nose pitch attitude should be controlled with elevator as usual. In a steep turn, if you need to raise the nose, it may be tempting to “rudder” the nose up, or hold the nose up with top rudder. This makes the turn uncoordinated and should not be done. You may, however, need to shallow the bank a little before raising the nose to minimize stress on the airplane. In a 60 degree steep bank turn, you may notice an overbanking tendency with the difference in airspeeds and lift between the left wing and the right wing.
6) C At touchdown, the longitudinal (tail to nose) axis of the airplane should be aligned parallel to the runway centerline. To compensate for a crosswind from the right, the wing must be banked to the right. This will cause the airplane to want to turn right to a new heading. To prevent this turning, you will need to hold left rudder while holding right aileron and right bank. You do not want to touchdown with the nose angled crooked into the wind. In the flare, just before touch down for a crosswind landing, you should control left and right drift with the bank attitude (ailerons) and keep the nose straight with rudder.
7) A In the last half of either Chandelle, you will need right rudder to compensate for torque effect, slipstream effect and p-factor. In the last half of the left-turning Chandelle, you are slowly rolling out of the turn by applying right aileron deflection. This use of the ailerons will produce a left-yawing tendency (adverse aileron yaw), which is now increasing the left yawing tendency caused by the other 3 forces. This will result in the need for more right rudder. In the right-turn Chandelle, you are slowly rolling out of the turn by applying left aileron deflection. The adverse aileron yaw produced by this use of the ailerons produces a right-yawing tendency. This will help you compensate for the left-yawing tendency of the other 3 forces and it will therefore require less right rudder.
8. C In the right turn portion of the Lazy 8 maneuver between the 45 degree point and the 90 degree point, you are simultaneously increasing bank angle to the right, while encountering the maximum p-factor from being at the highest pitch attitude at the 45 degree point. You are also pitching the nose down, which induces gyro precession that results in an increase in the left – yawing tendency that requires right rudder. In summary, this segment of the maneuver is the only segment where you have 5 forces producing a left-yawing tendency all together at the same time, requiring the maximum right rudder application. 1) Adverse aileron yaw from rolling to a steeper right bank, 2) Torque effect from climbing at a slower than cruise airspeed, 3) Slipstream effect from a slower airspeed with power, 4) Gyro precession from the lowering of the nose and 5) p-factor from the nose attitude being above the horizon until you reach the 90 degree point.
How did you do? Please let me know if these quizzes are useful for you. Thank You.
Great rudder usage review…even for a glider pilot, instructor, tail wheel pilot, and of course, former airline pilot. Nice job, Steve.
Great Stuff! I really like the last two explanations about commercial maneuvers!
question 2 answer is wrong..
p factor requires left rudder to compensate NOT right rudder
Thank you for your interest in this question on the quiz. It is assumed that this airplane is right side up and as stated in the conditions, the prop is a turning in front in a clockwise direction of rotation as viewed from the cockpit. P-Factor (Propeller Factor) is a simpler term used for the aerodynamic reaction for thrust from the propeller formally titled “asymmetrical disc loading”. At higher angles of attack with high power settings and slow airspeed (such as takeoff climb), this effect is most pronounced. A thorough explanation of this can be found in the current version of the FAA Pilot’s Handbook of Aeronautical knowledge (pages 5-32 and 5-33). Other noted authors such as William Kershner and Trevor Thom have written text books that include an excellent description of this aerodynamic principle.
A simpler description of this complex action is that at a higher angle of attack, the propeller blades, when in a near horizontal position through each rotation, exhibit a difference in the force of thrust when comparing the right side down swinging blade versus the left side up swinging blade. The down swinging blade would have a net higher angle of attack or “bite” while the left up swinging blade would have a smaller angle of attack or less “bite” through the air. This would shift the center of thrust from the center of the prop hub to the right side of the spinning propeller “disc”. This results in a turning moment to the left which produces a LEFT YAW, that must be countered with RIGHT RUDDER.
The answer I have given is correct, unless we are flying upside down. I cover all of the turning forces in great detail in my aerobatics course and demonstrate their effect in the aerobatic maneuvers. It makes more sense and it is more believable when you actually see the airplane reactions.