Back
Contact Us

Stability and Control 2:
Static, Dynamic, and Maneuvering Stability

Theoretical Course Content

In a combination of online course slides and self-study of USAF TPS [1] and USNTPS [2] references, you will develop a detailed theoretical understanding of:

  • Longitudinal static stability: analysis of longitudinal static stability, stick-fixed stability equation, aircraft component contributions, stick-fixed neutral point, elevator power, stick-fixed flight test relationship; hinge moments, stick-free stability equation, stick-free flight test relationship, apparent stick-free stability.
  • Lateral-directional static stability: contributions to directional stability from the individual Cn. stability derivatives, rudder-fixed and rudder-free directional stability and flight test relationships; contributions to static lateral stability from the individual Cl stability derivatives, controls-fixed and controls-free flight test relationships; rolling performance; lateral-directional static stability flight tests.
  • Longitudinal maneuvering stability: analysis of maneuvering flight; stick-fixed and stick-free pull-up and turn maneuvers, flight test relationships, center of gravity restrictions, maneuvering flight tests.
  • Longitudinal dynamic stability: linearized equation of motion, short period mode, phugoid mode, stability derivatives, flight tests (technique, data reduction/fitting methods).
  • Lateral-directional dynamic stability: linearized equations of motion, Dutch roll mode, spiral mode, roll mode, flight tests (technique and data reduction), roll-sideslip coupling.

Flight Test and Data Analysis Exercises

These flight tests are to be flown in a flight simulator like X-Plane on your home computer. The data recorded during these tests is then analyzed with the iPython notebooks in our flight test GitHub repository.

  • Longitudinal static stability: You will fly data collection missions with several CG locations, and use flight test relationships to determine the stick-fixed and the stick-free neutral point. You will verify that the stick-free neutral point lies ahead of the stick-fixed. If using a joystick without force feedback, you will use the position of the trim tab as a proxy in the stick-free investigation.
  • Lateral-directional static stability: You will conduct steady straight sideslip and aileron roll flight tests and infer stability information from the data using the flight test relationships developed in the theory part of the course.
  • Longitudinal maneuvering stability: You will perform flight tests using the turning maneuver method at several CG locations. Using flight test relationships, you will determine the stick-fixed and stick-free maneuver points. You will verify that the stick-free maneuver point lies ahead of the stick-fixed maneuver point, and that both maneuver points lie behind the neutral points obtained during the longitudinal static stability analysis above.
  • Longitudinal dynamic stability: You will excite the short period mode and the phugoid mode during flight tests. During data analysis, you will fit a exponentially decaying sine function to the data and determine the period of the oscillations and decay rate of their amplitude. What is the relationship between pitch angle, airspeed, and angle of attack during the phugoid?
  • Lateral-directional dynamic stability: You will perform flight tests to record data for the Dutch roll mode, spiral mode, and roll mode, and perform the corresponding analysis. The Dutch roll mode will require a similar fit like the phugoid, but exhibits a much faster decay rate and shorter oscillation period.

References

Contact Us about This Course