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Presentation Copyright © 2015
AvSport of Lock Haven
Precession Precision
Taming Turning Tendency
Prof. H. Paul Shuch, Ph.D., CFII LSRM-A/GL/WSC/PPC, iRMT Heavy
Chief Flight Instructor, Director of MaintenanceAvSport of Lock Haven
FAA Safety Team Lead Representative Piper Memorial Airport, Lock Haven PA
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Presentation Copyright © 2015
AvSport of Lock Haven
Precession Precision
A FAASTeam Wings Safety Seminar
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AvSport of Lock Haven
Precession Precision
• Sentimental Journey to Cub Haven• Piper Memorial Airport• AvSport of Lock Haven • Your FAA Safety Team
Brought to you by:
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AvSport of Lock Haven
Precession Precision
RATIONALE:Many pilots report (especially when flying Light
Sport Aircraft) that raising the nose causes the plane to yaw in one direction, and lowering it yaws them in the opposite direction. This gives LSAs a reputation for being instable (or squirrely). In fact, these aircraft are merely obeying natural laws. In this FAA Wings Safety Seminar, a retired physics professor will teach you how to anticipate, detect, and conquer gyroscopic precession.
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Presentation Copyright © 2015
AvSport of Lock Haven
Precession Precision
OBJECTIVES:Upon successful completion of this seminar, you will:
• Visualize Cartesian coordinates• Predict precession effects• Anticipate aircraft yaw response• Respond with decisive rudder• Overcome lateral instability• Avoid hitting the runway lights
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AvSport of Lock Haven
Precession Precision
Caveat:• The procedures shown here are used successfully by one
particular instructor, in one particular category and class of aircraft. They may not apply in your situation. Your mileage may vary.
Disclaimer:• Nothing in this presentation should be considered a substitute for
adequate dual training, conducted by an appropriately rated flight instructor familiar with your particular aircraft.
Waiver:• By viewing this presentation, you understand and agree that:
– Flying is a sport– There is risk associated with all sports– You accept that risk
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AvSport of Lock Haven
Precession Precision
Getting to know you…
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Precession Precision
Which of the following are you?(choose one that best describes you)
• Student Pilot• Sport Pilot• Private Pilot• Commercial Pilot / ATP• Flight Instructor
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AvSport of Lock Haven
Precession Precision
Introduction:
The Axis of Evil
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AvSport of Lock Haven
Precession Precision
Pitch, Roll, and Yaw Axes:
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AvSport of Lock Haven
Precession Precision
Rene Descartes(French mathematician and philosopher,
1596-1650)
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AvSport of Lock Haven
Precession Precision
CARTESIANCOORDINATES
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AvSport of Lock Haven
Precession Precision
Mutually Orthogonal
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AvSport of Lock Haven
Precession Precision
CARTESIANCOORDINATES
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AvSport of Lock Haven
Precession Precision
Quiz Time!
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AvSport of Lock Haven
Precession Precision
For purposes of this course, we will consider the direction in which the aircraft is traveling
to be:
• The X-axis• The Y-axis• The Z-axis• Any axis we choose• None of the above
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AvSport of Lock Haven
Precession Precision
PRINCIPLES OF THE GYROSCOPE
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Precession Precision
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Precession Precision
PRECESSION
(Z) (X)
(Y)
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Precession Precision
PRECESSION
(Z)
(X) (Y)
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Precession Precision
PRECESSION
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Precession Precision
PRECESSION
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AvSport of Lock Haven
Precession Precision
Another Question!
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Presentation Copyright © 2015
AvSport of Lock Haven
Precession Precision
If the aircraft is traveling down the runway (into the page), and you raise or lower the
nose, the plane will precess in:
• The X-axis• The Y-axis• The Z-axis• All three axes• None of the above
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AvSport of Lock Haven
Precession Precision
CARTESIANCOORDINATES
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Precession Precision
FOUR DEGREES
OF FREEDOM
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AvSport of Lock Haven
Precession Precision
AILERONS CONTROL ROLL(your bank control)
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Precession Precision
RUDDER CONTROLS YAW(your directional control)
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AvSport of Lock Haven
Precession Precision
ELEVATOR CONTROLS PITCH(your airspeed control)
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AvSport of Lock Haven
Precession Precision
THROTTLE CONTROLS POWER(your altitude control)
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Precession Precision
Sometimes, you just gotta dance!
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Precession Precision
Doh!
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Precession Precision
Gyroscopic precession is best corrected through application of
• elevator• rudder• ailerons• throttle• flaps
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AvSport of Lock Haven
Precession Precision
IF SOMETHING ROTATES,
IT CAN PRECESS
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Precession Precision
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Precession Precision
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Precession Precision
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Precession Precision
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Precession Precision
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Precession Precision
I know this one!
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Precession Precision
Gyroscopic precession is least evident in a(n)
• Airplane• Gyroplane• Powered parachute• Glider• Equally evident in all
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AvSport of Lock Haven
Precession Precision
TAKEOFFAND LANDINGARE TRICKIEST
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Precession Precision
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Precession Precision
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Precession Precision
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Precession Precision
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Precession Precision
Final Question!
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AvSport of Lock Haven
Precession Precision
Gyroscopic precession can be observed during:
• Rotation• Flare• Go-around• Power-on stalls• Any of the above
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AvSport of Lock Haven
Precession Precision
A Final Thought
Which way will you precess? It depends…
Is the engine direct drive, or geared?
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Precession Precision
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Precession Precision
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Precession Precision
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