Comprehensive System Identification of Ducted Fan UAVs - Cal Poly
Comprehensive System Identification of Ducted Fan UAVs - Cal Poly
Comprehensive System Identification of Ducted Fan UAVs - Cal Poly
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It is known that the dummy was placed directly on top <strong>of</strong> the platform, so it isassumed that the drag will have a moment arm <strong>of</strong> 3 feet above the platform, or half theheight <strong>of</strong> the plate used to approximate the drag. This allows the determination <strong>of</strong>moment produced with airspeed due to the dummy. This is calculated and then subtractedfrom the actual data in Figure 3.15 to produce Figure 3.17.Pitching Moment (ft-lbs)450400350300250200150100500Hiller Test ResultsApproximate Dummy MomentApproximate Duct PitchingMomentLinear Fit for 20 knts0 20 40 60 80Speed (fps)Figure 3.17 – Results <strong>of</strong> Removing Dummy Moment from Hiller Platform TestIt can be seen that the moment from the dummy is increasing with truck speed.Removing the effect <strong>of</strong> the dummy produces the green line. This is then used to fit a lineto determine the average slope from 0 to 20 knots (33.8 fps). This slope <strong>of</strong> this dashedline is the dimensional pitching moment derivative, M u .- 50 -