Comprehensive System Identification of Ducted Fan UAVs - Cal Poly

Table 3.13 reveals that this method may not be accounting for the entirety ofdominant characteristics for ducted fan vehicles. This is seen in the way the Solotrekdiffers from the other smaller chord vehicles. To account for more specific geometries, amethod which better characterizes the propellers was also investigated. Thisnondimensionalization uses the chord and radius of the rotating propellers tonondimensionalize the pitching moment:CM=σ π=M( Ω ) 2ρσ A R RbcRM ~ pitching momentρ ~densityΩ ~ blade rotation speed (rad/sec)R ~ duct radiusA ~ duct areab ~ # of bladesc ~ mean blade chordTable 3.14 represents the results of this method.Table 3.14 – Pitching Moment with Blade Chord SummaryVehiclePitching Moment Derivative M u⎛ ⎞ft-lb⎜ ⎟⎜ft ⎟⎝ sec ⎠NondimensionalC MuFlying Platform 5.11 4.48 x 10 -4Wind Tunnel 0.011 1.03 x 10 -4OAVFlight Test 0.00643 6.15 x 10 -41,800 RPM 1.034 2.90 x 10 -42,200 RPM 1.376 2.58 x 10 -4Solotrek2,600 RPM 1.933 2.60 x 10 -43,000 RPM 2.589 2.61 x 10 -4Wind Tunnel 0.00323 2.45 x 10 -5i-Star 9”Flight Test 0.5014 3.80 x 10 -3i-Star 29” 0.11652 5.20 x 10 -5This method yields values similar to the previous methods in Table 3.13. Thenumbers here are more closely related and show that the nondimensionalization is an- 54 -