cubdriver2
FRIEND
Gitting Rid of the Rust...What Sort of Routine to Do in 30- 60 Minutes of Flight
- Thread starter WindOnHisNose
- Start date
WindOnHisNose
BENEFACTOR
Lino Lakes MN (MY18)
In response to your "huh?", of course the exercise is to become comfortable and good at uncoordinated flight.
Here is the "Dutch Roll" taken from Hal Terry's book Fly the Wild and Stay Alive:
APPENDIX A TO CHAPTER ONE – THE PRECISION DUTCH ROLL MANEUVER
OBJECTIVE: To become familiar with the use of the flight controls for all three axes, while in a precise cross-controlled slip, to the degree that the pilot will develop the ability to make wing-down cross-wind landings with smoothness, accuracy, and ease.
PROCEDURE: Select an altitude that will allow an inadvertent spin entry and recovery with at least 2000 ft AGL remaining. (The maneuver is very slow and mild if done correctly. If the aircraft stalls in the slip the high wing can be expected to drop sharply and an immediate application of forward stick and neutral or opposite rudder, avoiding the use of ailerons, should effect recovery with little loss of altitude.)
If your airplane has a “Both Tanks” fuel selection, use that position to avoid the possibility of unporting a single, selected tank outlet. If “Both” is not available, the fuel tanks should be three-fourths or more full.
Establish approach airspeed and landing configuration, approach power, with about half flaps. Fly the maneuver level or very shallow descent. Do not get slower than Vs0 plus 5 knots, or a few knots above stall buffet, whichever is higher. But once you start the maneuver, the safety pilot can help warn you about too-slow speed. You should be looking forward at the nose of the airplane with respect to the reference point. You should have a CFI or qualified safety pilot aboard because you will be concentrating on looking forward during the maneuver.
Pick a distant object like a peak or cloud and point the nose below it. Then, if level and on speed, start the maneuver by slowly rolling the aircraft to achieve a steadily increasing bank, while at the same time using rudder control to hold the nose under the reference point. Add a little power to hold airspeed.
Use elevator control to counteract rudder effects and prevent the nose from rising. Your rudder inputs will also influence aileron effectiveness. Upon reaching 15-20 degrees of bank, or when you no longer have enough rudder available to hold heading, stop rolling briefly (five to ten seconds) and hold the nose steady below the reference point. Now, start rolling slowly in the opposite direction - don’t come off the top rudder too soon or you’ll “scoop” out. Don’t anticipate how much rudder you’ll need – use only what is needed, when you need it.
The technique of using only the rudder that you need when you need it is crucial to developing your cross-control skill. The measure of your success is doing what’s needed to hold the nose steadily in place.
This maneuver can be very frustrating but keep plugging and you’ll learn it well. Remember, you’ll be in a slip, with the ball towards the low wing and using “high rudder” to hold the nose steady. This is the way the controls will be used in a wing-down cross-wind landing, except that in this practice maneuver your sole reference is to keep the airplane aligned with respect to the reference point. You are simply learning control actions and interactions in the cross-control slip. In the actual wing-down cross-wing landing you’ll be varying the bank to stop the sidewise drift you see on the runway, while maintaining heading alignment with the rudder.
During your practice, add a little power at the start and don’t get too slow or go below a previously designated altitude. Once you are comfortable and fairly smooth with the maneuver, you’re ready to practice the real thing. Remember, rudder controls alignment/heading, ailerons control angle of bank for drift control, and elevators smoothly flare the pitch while resisting those pesky inputs from the cross-controlled ailerons and rudder.
Fly the maneuver both with and without power. Notice the effect that power has on rudder and elevator effectiveness, and how that will change a little when you change direction (left/right) of the slip. Notice that lowering landing flaps will reduce your rudder authority. IMPORTANT: Don’t slip with flaps down if it is prohibited in your model of airplane. It’s no fun to suddenly go nose-down ballistic with loss of elevator control!
Randy
Here is the "Dutch Roll" taken from Hal Terry's book Fly the Wild and Stay Alive:
APPENDIX A TO CHAPTER ONE – THE PRECISION DUTCH ROLL MANEUVER
OBJECTIVE: To become familiar with the use of the flight controls for all three axes, while in a precise cross-controlled slip, to the degree that the pilot will develop the ability to make wing-down cross-wind landings with smoothness, accuracy, and ease.
PROCEDURE: Select an altitude that will allow an inadvertent spin entry and recovery with at least 2000 ft AGL remaining. (The maneuver is very slow and mild if done correctly. If the aircraft stalls in the slip the high wing can be expected to drop sharply and an immediate application of forward stick and neutral or opposite rudder, avoiding the use of ailerons, should effect recovery with little loss of altitude.)
If your airplane has a “Both Tanks” fuel selection, use that position to avoid the possibility of unporting a single, selected tank outlet. If “Both” is not available, the fuel tanks should be three-fourths or more full.
Establish approach airspeed and landing configuration, approach power, with about half flaps. Fly the maneuver level or very shallow descent. Do not get slower than Vs0 plus 5 knots, or a few knots above stall buffet, whichever is higher. But once you start the maneuver, the safety pilot can help warn you about too-slow speed. You should be looking forward at the nose of the airplane with respect to the reference point. You should have a CFI or qualified safety pilot aboard because you will be concentrating on looking forward during the maneuver.
Pick a distant object like a peak or cloud and point the nose below it. Then, if level and on speed, start the maneuver by slowly rolling the aircraft to achieve a steadily increasing bank, while at the same time using rudder control to hold the nose under the reference point. Add a little power to hold airspeed.
Use elevator control to counteract rudder effects and prevent the nose from rising. Your rudder inputs will also influence aileron effectiveness. Upon reaching 15-20 degrees of bank, or when you no longer have enough rudder available to hold heading, stop rolling briefly (five to ten seconds) and hold the nose steady below the reference point. Now, start rolling slowly in the opposite direction - don’t come off the top rudder too soon or you’ll “scoop” out. Don’t anticipate how much rudder you’ll need – use only what is needed, when you need it.
The technique of using only the rudder that you need when you need it is crucial to developing your cross-control skill. The measure of your success is doing what’s needed to hold the nose steadily in place.
This maneuver can be very frustrating but keep plugging and you’ll learn it well. Remember, you’ll be in a slip, with the ball towards the low wing and using “high rudder” to hold the nose steady. This is the way the controls will be used in a wing-down cross-wind landing, except that in this practice maneuver your sole reference is to keep the airplane aligned with respect to the reference point. You are simply learning control actions and interactions in the cross-control slip. In the actual wing-down cross-wing landing you’ll be varying the bank to stop the sidewise drift you see on the runway, while maintaining heading alignment with the rudder.
During your practice, add a little power at the start and don’t get too slow or go below a previously designated altitude. Once you are comfortable and fairly smooth with the maneuver, you’re ready to practice the real thing. Remember, rudder controls alignment/heading, ailerons control angle of bank for drift control, and elevators smoothly flare the pitch while resisting those pesky inputs from the cross-controlled ailerons and rudder.
Fly the maneuver both with and without power. Notice the effect that power has on rudder and elevator effectiveness, and how that will change a little when you change direction (left/right) of the slip. Notice that lowering landing flaps will reduce your rudder authority. IMPORTANT: Don’t slip with flaps down if it is prohibited in your model of airplane. It’s no fun to suddenly go nose-down ballistic with loss of elevator control!
Randy
CamTom12
Registered User
Huntsville, AL
Dutch roll, other than the coordination exercise, is a slang term for a lateral-directional oscillation(LDO), and is a nuisance mode. If it's divergent in nature (primary cause would be poor design) it is likely unrecoverable. Your cub by design has a convergent LDO, and you can set it off by holding a slip in forward flight so that your heading remains constant, then release all the flight controls to their normal positions and watch (hands and feet off the controls or you'll contaminate the result). The easiest way to characterize the motion is to follow the line one of your wingtips traces on the sky (football pointed forward or upward, maybe circular, etc). Eventually, without your intervention, the nuisance motion will dampen out and you'll be straight and level again.
The pitch axis has a nuisance oscillatory mode as well (phugoid, or the long term mode). If divergent, both modes are highly likely to be unrecoverable and would have precluded the airplane's design certification.
EDIT: here's a video: https://youtu.be/1_TW9oz99NQ
Last edited:
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