Comprehensive System Identification of Ducted Fan UAVs - Cal Poly

Techsburg) the pitching moment response to gusts was analyzed. Figure 3.13 shows asummary of the data collected for the pitching moment.i-Star-9 Pitching Moment Characteristics0.4Pitching Moment (ft-lb)0.20-0.2-0.4-0.6-0.8-10 20 40 60 80 100 120 140Shroud Velocity (fps)Figure 3.13 – Pitching Moment Wind Tunnel Test Data for i-Star 9”Figure 3.13 shows that a linearization was completed for the first 30 knots and isshown. The slope of this line represents the dimensional derivative M u . What is curioushere, and will be discussed in further detail in the next sections, is the nature of thepitching moment response to increases in speed. As the vehicle experiences a cross windin hover, it will pitch in the positive direction. This represents a corrective moment.However if the gust is strong enough, it will actually experience a negative moment.The method illustrated above was repeated for all of the major flight derivativesto obtain the values portrayed in Table 3.11. Table 3.11 compares both 9” and 29”vehicles as well as the 9” flight test results where appropriate.- 43 -